btrfs: free qgroup reserve when ORDERED_IOERR is set

An ordered extent completing is a critical moment in qgroup reserve
handling, as the ownership of the reservation is handed off from the
ordered extent to the delayed ref. In the happy path we release (unlock)
but do not free (decrement counter) the reservation, and the delayed ref
drives the free. However, on an error, we don't create a delayed ref,
since there is no ref to add. Therefore, free on the error path.

CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>