intel-ipu6: CSE authenticate_run failed + error -EIO: FW authentication failed

I get the following error on kernel 6.12.1 with a custom kernel config
```
intel-ipu6 0000:00:05.0: enabling device (0000 -> 0002)
intel-ipu6 0000:00:05.0: IPU6 in secure mode touch 0x80000000 mask 0x0
Loading firmware: intel/ipu/ipu6epmtl_fw.bin
intel-ipu6 0000:00:05.0: FW version: 20230925
intel-ipu6 0000:00:05.0: Found supported sensor OVTI08F4:00
intel-ipu6 0000:00:05.0: Connected 1 cameras
intel-ipu6 0000:00:05.0: Sending BOOT_LOAD to CSE
intel-ipu6 0000:00:05.0: Sending AUTHENTICATE_RUN to CSE
intel-ipu6 0000:00:05.0: expected resp: 0x2, IPC response: 0xd20
intel-ipu6 0000:00:05.0: CSE authenticate_run failed
intel-ipu6 0000:00:05.0: error -EIO: FW authentication failed
intel-ipu6 0000:00:05.0: probe with driver intel-ipu6 failed with error -5
```

Expected behaviour: AUTHENTICATE_RUN should succeed.

A necessary kernel option might be missing in the custom kernel configuration, because FW loading works with the distribution-provided kernel. However, if this was indeed the reason, that would indicate a issue with Kconfig for the IPU6 driver as Kconfig should ensure that the kernel includes all necessary options.

Pastebins:

- [kernel-6.12.1-gentoo-dist, working](https://pastebin.com/q1Tnzw69)
- [kernel-6.12.1-custom, CSE authenticate_run fails](https://pastebin.com/rmKdRR6q)