[BUG] mt7921e: TDLS key addition failure causes complete TX/RX interface lockup during 802.11z negotiation

### Pre-flight checklist
- [x] I have searched existing issues and this is not a duplicate.
- [x] I have read the [Contributing Guidelines](https://github.com/CachyOS/linux-cachyos/blob/master/CONTRIBUTING.md).
- [x] I have verified the issue is reproducible with the latest available CachyOS kernel.
- [x] I have tried to reproduce the issue on Arch Linux's `linux` kernel.

### Upstream / vanilla kernel check
I have not tested with a vanilla/upstream kernel

### Kernel variant
linux-cachyos (EEVDF, Clang)

### System information (cachyos-bugreport.sh)
- **OS:** CachyOS (Kernel 7.1.8-1-cachyos x86_64)
- **CPU:** AMD Ryzen 5 7640HS w/ Radeon 760M Graphics
- **Wi-Fi Hardware:** MEDIATEK Corp. MT7921 802.11ax PCIe Wireless Network Adapter [Filogic 330] [14c3:7961]
- **Subsystem:** AzureWave Device [1a3b:4682]
- **Driver:** `mt7921e` (in-tree)
- **Firmware:** HW/SW: 0x8a108a10 (Build: 20260224110909a), WM Firmware Version: ____010000 (Build: 20260224110949)
- **Wireless Stack:** `wpa_supplicant 2.12` / `NetworkManager`

### Bug description
When an external wireless peer on the same local BSSID (e.g., an Android device) initiates an 802.11z TDLS (Tunneled Direct Link Setup) request during peer-to-peer IP traffic (such as an SSH session over local IP or Tailscale direct peer communication), `wpa_supplicant` attempts to install the TDLS Pairwise Key (TPK) into the `mt7921e` kernel driver via `nl80211`.

The kernel driver rejects the key addition with `kernel reports: key addition failed`. Immediately following this failure, the MT7921 interface (`wlan0`) enters a hung state where it completely stops transmitting and receiving frames. All network connectivity drops indefinitely on the host until the wireless interface is hard-toggled via `rfkill` / NetworkManager restart.

### Steps to reproduce
1. Connect a machine equipped with a MediaTek MT7921 adapter to an 802.11ax/ac Wi-Fi AP using `NetworkManager` with default `wpa_supplicant`.
2. Connect another device that supports/triggers 802.11z TDLS (such as a Samsung Galaxy Android smartphone) to the same Wi-Fi network.
3. Initiate direct peer-to-peer traffic between the two devices (e.g. SSH into the laptop from the phone over local Wi-Fi or direct Tailscale socket).
4. Once the phone sends TDLS discovery / setup requests, the MT7921 driver fails on TPK key configuration.
5. All subsequent IP traffic on `wlan0` times out / drops until Wi-Fi is restarted.

### Expected behavior
The driver should either successfully configure the TDLS TPK encryption key, or gracefully ignore/reject the TDLS setup request without corrupting the active TX/RX queue / PHY state.

### Actual behavior
The driver rejects the key and permanently wedges the interface until restart:
```text
wpa_supplicant: TDLS: Creating peer entry for ce:8e:61:eb:5b:29
wpa_supplicant: TDLS: Dialog Token in TPK M1 1
wpa_supplicant: wlan0: nl80211: kernel reports: key addition failed
wpa_supplicant: TDLS: Failed to set TPK to the driver
```

### Logs / stack traces

System journal logs

```text
Aug 17 03:27:17 tito-cachyos sshd-session[59964]: Accepted publickey for nozomi from 100.125.253.5 port 59376 ssh2: ED25519
Aug 17 03:27:17 tito-cachyos sshd-session[59964]: pam_unix(sshd:session): session opened for user nozomi(uid=1000) by nozomi(uid=0)
Aug 17 03:27:19 tito-cachyos wpa_supplicant[808]: TDLS: Creating peer entry for ce:8e:61:eb:5b:29
Aug 17 03:27:21 tito-cachyos wpa_supplicant[808]: TDLS: Dialog Token in TPK M1 1
Aug 17 03:27:21 tito-cachyos wpa_supplicant[808]: wlan0: nl80211: kernel reports: key addition failed
Aug 17 03:27:21 tito-cachyos wpa_supplicant[808]: TDLS: Failed to set TPK to the driver
Aug 17 03:27:47 tito-cachyos tailscaled[807]: open-conn-track: timeout opening ...
Aug 17 03:27:48 tito-cachyos tailscaled[807]: netcheck: UDP is blocked, trying HTTPS
Aug 17 03:27:48 tito-cachyos tailscaled[807]: netcheck: UDP is blocked, trying ICMP
```

### Additional system information & Workaround
- **Workaround:** Switching NetworkManager backend to `iwd` (`/etc/NetworkManager/conf.d/wifi_backend.conf` -> `wifi.backend=iwd`) solves the issue completely since `iwd` does not negotiate the failing TDLS handshake.

Reproduce the TDLS negotiation with the mt7921e adapter and inspect the wpa_supplicant, nl80211, and driver messages around TPK key installation. The only configuration path mentioned is /etc/NetworkManager/conf.d/wifi_backend.conf, where switching to iwd avoids the failure. Done means a rejected or accepted TDLS setup no longer wedges wlan0, with subsequent traffic continuing without an interface restart.

Written by the indexing model from the issue text.