Btrfs: Fix memory leak in cache_drop_leaf_ref

The code wasn't doing a kfree on the sorted array

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1d3e926..7527523 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3582,6 +3582,7 @@
 		info++;
 	}
 
+	kfree(sorted);
 	return 0;
 }