drm/amdgpu: further move TLB hw workarounds a layer up

For the PASID flushing we already handled that at a higher layer, apply
those workarounds to the standard flush as well.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>