drm/amdgpu: pin shared GWS, GDS and OA resources

They can't move anyway, but just to be clean here.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>