drm/amdgpu: add warning to amdgpu_bo_gpu_offset() v2

Check if there really is a valid offset for the BO.

v2: user WARN_ON_ONCE
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com> (v1)
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_object.h

@@ -96,6 +96,7 @@ static inline void amdgpu_bo_unreserve(struct amdgpu_bo *bo)
  */
 static inline u64 amdgpu_bo_gpu_offset(struct amdgpu_bo *bo)
 {
+	WARN_ON_ONCE(bo->tbo.mem.mem_type == TTM_PL_SYSTEM);
 	return bo->tbo.offset;
 }