ttm: on move memory failure don't leave a node dangling

if we have a move notify callback, when moving fails, we call move notify
the opposite way around, however this ends up with *mem containing the mm_node
from the bo, which means we double free it. This is a follow on to the previous
fix.

Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/ttm/ttm_bo.c

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 33d20be..52b20b1 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -434,6 +434,7 @@
 			bo->mem = tmp_mem;
 			bdev->driver->move_notify(bo, mem);
 			bo->mem = *mem;
+			*mem = tmp_mem;
 		}
 
 		goto out_err;