drm/amdgpu: Add query_ras_error_count for vcn v4_0_3

Add query_ras_error_count callback for vcn v4_0_3.
It will be used to query and log vcn error count.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>