xfs: lock dquot buffer before detaching dquot from b_li_list

We have to lock the buffer before we can delete the dquot log item from
the buffer's log item list.

Cc: stable@vger.kernel.org # v6.13-rc3
Fixes: acc8f862 ("xfs: attach dquot buffer to dquot log item buffer")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>