drm/amdgpu: unbind GTT only when it is bound

Doesn't make much sense to clear the GTT when it was never filled.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -733,6 +733,9 @@ static int amdgpu_ttm_backend_unbind(struct ttm_tt *ttm)
 {
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
 
+	if (!amdgpu_ttm_is_bound(ttm))
+		return 0;
+
 	/* unbind shouldn't be done for GDS/GWS/OA in ttm_bo_clean_mm */
 	if (gtt->adev->gart.ready)
 		amdgpu_gart_unbind(gtt->adev, gtt->offset, ttm->num_pages);