libxfs: deferred items should call xfs_perag_intent_{get,put}

Make the intent item _get_group and _put_group functions call
xfs_perag_intent_{get,put} to match the kernel.  In userspace they're
the same thing so this makes no difference.  However, let's not leave
unnecessary discrepancies.

Fixes: 7cb26322f74 ("xfs: allow queued AG intents to drain before scrubbing")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>