Bug#1106268: linux-image-6.12.29-amd64: amdgpu DMCUB errors and lockups new in v6.12.29

[Axel Regnat]

Today 6.12.30 landed in testing and is affected by this. So after a few 
minutes my system freezes and I can only use Magic SysRQ to reboot.

6.12.27 works fine so I'll have to stick for this kernel till this is fixed.