btrfs: use btrfs_put_fs_root to free roots always

If we are going to track leaked roots we need to free them all the same
way, so don't kfree() roots directly, use btrfs_put_fs_root.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tests/btrfs-tests.c

@@ -227,7 +227,7 @@ void btrfs_free_dummy_root(struct btrfs_root *root)
 		/* One for allocate_extent_buffer */
 		free_extent_buffer(root->node);
 	}
-	kfree(root);
+	btrfs_put_fs_root(root);
 }
 
 struct btrfs_block_group *