drm/amd/pm: fix some OEM SKU specific stability issues

commit e3f38248

 upstream.

Add a quirk in sienna_cichlid_ppt.c to fix some OEM SKU
specific stability issues.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>