drm/nouveau: uvmm: remove incorrect calls to mas_unlock()

Remove incorrect calls to mas_unlock() in the unwind path of
__nouveau_uvma_region_insert(). The region maple tree uses an external
lock instead, namely the global uvmm lock.

Fixes: b88baab ("drm/nouveau: implement new VM_BIND uAPI")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230807163238.2091-5-dakr@redhat.com

drivers/gpu/drm/nouveau/nouveau_uvmm.c

@@ -279,15 +279,11 @@ __nouveau_uvma_region_insert(struct nouveau_uvmm *uvmm,
 	u64 last = addr + range - 1;
 	MA_STATE(mas, &uvmm->region_mt, addr, addr);
 
-	if (unlikely(mas_walk(&mas))) {
-		mas_unlock(&mas);
+	if (unlikely(mas_walk(&mas)))
 		return -EEXIST;
-	}
 
-	if (unlikely(mas.last < last)) {
-		mas_unlock(&mas);
+	if (unlikely(mas.last < last))
 		return -EEXIST;
-	}
 
 	mas.index = addr;
 	mas.last = last;