drm/amdgpu: correct query xgmi3x16 pcs error status

There is xgmi3x16 pcs error status for aldebaran, driver should
check xgmi3x16 pcs error status field instead of gopx16 pcs error
status field.

Signed-off-by: Stanley.Yang <Stanley.Yang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>