drm/amdgpu: add GMC ip block for GC 9.4.3

Add GMC IP handling for GC 9.4.3

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