drm/amdgpu: Add msix restore for pass-through mode

In pass-through mode, after mode 1 reset, msix enablement status would
lost and never receives interrupt again. So, we should restore msix
status after mode 1 reset.

Signed-off-by: Chengzhe Liu <ChengZhe.Liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>