drm/amdgpu: update mmhub 1.7 ras error reporting

only output ras error status if an error bit is set

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: John Clements <john.clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>