ubifs: dereferencing an ERR_PTR in ubifs_mount()

d251ed271d5 "ubifs: fix sget races" left out the goto from this
error path so the static checkers complain that we're dereferencing
"sb" when it's an ERR_PTR.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ubifs/super.c

@@ -2146,6 +2146,7 @@ static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
 	if (IS_ERR(sb)) {
 		err = PTR_ERR(sb);
 		kfree(c);
+		goto out_close;
 	}
 
 	if (sb->s_root) {