[amdgpu SI] multigpu setup crashes during boot when dpm=1

Submitted by Arek Ruśniak

Assigned to Default DRI bug account

Link to original bug (#97634)

Description

Created attachment 126300
kernel log

tested on drm-next-4.9-wip:

1. 832c6ef + 2 patches from Tom and Michel (another bugs)
   
2. 2c0d731
   the same behavior on both.
   

With dpm=0 amdgpu doesn't complain and works with intel.

Hard to say it's regression because when I tried DRI_PRIME few month ago dpm didn't work at all.

**Attachment 126300**, "kernel log":
prime.dmesg