[BUG] RX 7900 XTX HDMI output shows “connected” but no picture on TV after kernel 7.2.0 + mesa 26.2.1 update

### 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)

```text
DISPLAY ERROR
```

### Manual system information (if cachyos-bugreport.sh is unavailable)

```text
- GPU: AMD Radeon RX 7900 XTX
- CPU: Ryzen 7 9700x
- RAM: 64gb DDR5
-MOTHERBOARD B650
- Kernel: 7.2.0-1 (previously working fine on 7.1.8-1)
- Mesa: 3:26.2.1-1 (previously working fine on 3:26.2.0-1)
- Desktop: KDE Plasma, Wayland
- Display: TV connected via HDMI-A-1
```

### Bug description

After today's system update (linux-cachyos 7.1.8 → 7.2.0, mesa 26.2.0 → 26.2.1),
my TV connected via HDMI-A-1 shows as "connected" in KDE Display Settings and
kscreen-doctor, but displays no picture at all — screen stays completely blank
on the TV side.

xrandr shows the TV's active mode as 4608x2592, a non-standard resolution
(exactly 1.2x scaled 3840x2160). This suggests the EDID read or mode
negotiation is failing and a synthetic/incorrect mode is being generated
that the TV can't sync to.

Troubleshooting done:
- Tried multiple HDMI ports and cables — no change
- Set display scale to 100% (was 125%) — no change
- Confirmed NOT a hardware/cable/TV issue: dual-booted into Windows on the
same machine, same cable, same TV — displays perfectly at native 4K

journalctl -b -p err | grep -i amdgpu output

### Steps to reproduce

Latest Update

### Expected behavior

I expect it to work I just updated my pc after a week it was working perfectly fine yesterday until I updated it today

### Actual behavior

My display settings is saying my tv is connected but it’s not showing on my screen but windows works perfectly fine I’m duel booting

### Logs / stack traces

```text

```

### Additional system information

_No response_