drm/amdgpu: release the VM shadow in the error path as well

Without it we run into a memory leak.
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>

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

@@ -411,6 +411,7 @@ static int amdgpu_vm_alloc_levels(struct amdgpu_device *adev,
 
 			r = amdgpu_vm_clear_bo(adev, vm, pt, level, ats);
 			if (r) {
+				amdgpu_bo_unref(&pt->shadow);
 				amdgpu_bo_unref(&pt);
 				return r;
 			}
@@ -418,6 +419,7 @@ static int amdgpu_vm_alloc_levels(struct amdgpu_device *adev,
 			if (vm->use_cpu_for_update) {
 				r = amdgpu_bo_kmap(pt, NULL);
 				if (r) {
+					amdgpu_bo_unref(&pt->shadow);
 					amdgpu_bo_unref(&pt);
 					return r;
 				}