drm/amdgpu: Don't warn on destroying a pinned BO

The warning turned out to be not so useful, as BO destruction tends to
be deferred to a workqueue.

Also, we should be preventing any damage from this now, so not really
important anymore to fix code doing this.
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Tested-by: NMike Lothian <mike@fireburn.co.uk>
Signed-off-by: NMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -89,7 +89,7 @@ static void amdgpu_ttm_bo_destroy(struct ttm_buffer_object *tbo)
 	struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
 	struct amdgpu_bo *bo = ttm_to_amdgpu_bo(tbo);
 
-	if (WARN_ON_ONCE(bo->pin_count > 0))
+	if (bo->pin_count > 0)
 		amdgpu_bo_subtract_pin_size(bo);
 
 	if (bo->kfd_bo)