xfs: remove the leftover xfs_{set,clear}_li_failed infrastructure

Marking a log item as failed kept a buffer reference around for
resubmission of inode and dquote items.

For inode items commit 298f7bec ("xfs: pin inode backing buffer to
the inode log item") started pinning the inode item buffers
unconditionally and removed the need for this.  Later commit acc8f862
("xfs: attach dquot buffer to dquot log item buffer") did the same for
dquot items but didn't fully clean up the xfs_clear_li_failed side
for them.  Stop adding the extra pin for dquot items and remove the
helpers.

This happens to fix a call to xfs_buf_free with the AIL lock held,
which would be incorrect for the unlikely case freeing the buffer
ends up calling vfree.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>