drm/amdgpu: initialize PSP before IH under SR-IOV

In order to support new PSP feature that PSP may provide interface
to program IH CNTL register, initialize PSP before IH under Vega10
SR-IOV VF

Signed-off-by: Trigger Huang <Trigger.Huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>