ttm: use NULL instead of 0 for ttm_bo_reserve()'s pointer arg.

Fix a sparse warning: ttm_bo_reserve()'s last argument is a
pointer to a struct, so use NULL as nullpointer.

Signed-off-by: Martin Kepplinger <martink@posteo.de>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index a13a100..3da89d5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -412,7 +412,7 @@
 	int ret;
 
 	spin_lock(&glob->lru_lock);
-	ret = __ttm_bo_reserve(bo, false, true, false, 0);
+	ret = __ttm_bo_reserve(bo, false, true, false, NULL);
 
 	spin_lock(&bdev->fence_lock);
 	(void) ttm_bo_wait(bo, false, false, true);
@@ -514,7 +514,7 @@
 			return ret;
 
 		spin_lock(&glob->lru_lock);
-		ret = __ttm_bo_reserve(bo, false, true, false, 0);
+		ret = __ttm_bo_reserve(bo, false, true, false, NULL);
 
 		/*
 		 * We raced, and lost, someone else holds the reservation now,
@@ -577,11 +577,11 @@
 			kref_get(&nentry->list_kref);
 		}
 
-		ret = __ttm_bo_reserve(entry, false, true, false, 0);
+		ret = __ttm_bo_reserve(entry, false, true, false, NULL);
 		if (remove_all && ret) {
 			spin_unlock(&glob->lru_lock);
 			ret = __ttm_bo_reserve(entry, false, false,
-					       false, 0);
+					       false, NULL);
 			spin_lock(&glob->lru_lock);
 		}
 
@@ -726,7 +726,7 @@
 
 	spin_lock(&glob->lru_lock);
 	list_for_each_entry(bo, &man->lru, lru) {
-		ret = __ttm_bo_reserve(bo, false, true, false, 0);
+		ret = __ttm_bo_reserve(bo, false, true, false, NULL);
 		if (!ret)
 			break;
 	}
@@ -1595,7 +1595,7 @@
 	 * Using ttm_bo_reserve makes sure the lru lists are updated.
 	 */
 
-	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);
+	ret = ttm_bo_reserve(bo, true, no_wait, false, NULL);
 	if (unlikely(ret != 0))
 		return ret;
 	spin_lock(&bdev->fence_lock);
@@ -1630,7 +1630,7 @@
 
 	spin_lock(&glob->lru_lock);
 	list_for_each_entry(bo, &glob->swap_lru, swap) {
-		ret = __ttm_bo_reserve(bo, false, true, false, 0);
+		ret = __ttm_bo_reserve(bo, false, true, false, NULL);
 		if (!ret)
 			break;
 	}