drm/amdgpu: Avoid VF for RAS recovery source check

VF device sets the RAS flag when mailbox data can't be read properly.
There is no conclusive way to tell if the real source is RAS error.
Therefore VF schedules a KFD based reset which doesn't set RAS source.
SKip checking RAS source for any VF scheduled recovery.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reported-by: Vojislav Tomasevic <vojislav.tomasevic@amd.com>
Reviewed-by: Yiqing Yao <yiqing.yao@amd.com>
Tested-by: Yiqing Yao <yiqing.yao@amd.com>

Fixes: 2211660c ("drm/amdgpu: Prefer RAS recovery for scheduler hang")