xfs: hoist intent done flag setting to ->finish_item callsite

Each log intent item's ->finish_item call chain inevitably includes some
code to set the dirty flag of the transaction.  If there's an associated
log intent done item, it also sets the item's dirty flag and the
transaction's INTENT_DONE flag.  This is repeated throughout the
codebase.

Reduce the LOC by moving all that to xfs_defer_finish_one.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>