drm/ttm: partial revert "cleanup ttm_tt_(unbind|destroy)" v3

We still need to unbind explicitly during a move.

This partial reverts commit ff20caa0bcbfef9f7686f8d1868a3b990921afd6.

v2: remove unnecessary check and unused variable
v3: fix typo in commit message

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 4da0e78..2df602a 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -53,6 +53,7 @@
 	int ret;
 
 	if (old_mem->mem_type != TTM_PL_SYSTEM) {
+		ttm_tt_unbind(ttm);
 		ttm_bo_free_old_node(bo);
 		ttm_flag_masked(&old_mem->placement, TTM_PL_FLAG_SYSTEM,
 				TTM_PL_MASK_MEM);