lib/maple_tree.c: fix build error due to hotfix alteration

Commit 0de56e38 ("maple_tree: use maple state end for write
operations") was broken by a later patch "maple_tree: do not preallocate
nodes for slot stores".  But the later patch was scheduled ahead of
0de56e38, for 6.7-rc.

This fixlet undoes the damage.

Fixes: 0de56e38 ("maple_tree: use maple state end for write operations")
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/maple_tree.c

@@ -5477,7 +5477,7 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
 	node_size = mas_wr_new_end(&wr_mas);
 
 	/* Slot store, does not require additional nodes */
-	if (node_size == wr_mas.node_end) {
+	if (node_size == mas->end) {
 		/* reuse node */
 		if (!mt_in_rcu(mas->tree))
 			return 0;