drm/amdgpu: AMDGPU unusable since 6.12.1 and it looks like no one cares.

[Pavel Nikulin]

I think it persists as of 6.12.9 and today's firmware version from git.

Hardware Asus um5606

It only happens when the AC adaptor is disconnected, and the screen
refresh frequency is set to 120hz. It does not happen on any other
refresh frequency, or when the charger is connected.

It might be happening in Windows, but at much lower rate, like once in
a month. The windows version might be applying some mitigations.

Trying to catch what may be a prelude to hang never worked. It's just
instahang, without panic, or anything. I cannot debug it without
JTAGing the CPU, for which I have no equipment, nor am I sure if there
are even JTAG headers exposed on the laptop motherboard.