xfs: split xfs_zone_record_blocks

xfs_zone_record_blocks not only records successfully written blocks that
now back file data, but is also used for blocks speculatively written by
garbage collection that were never linked to an inode and instantly
become invalid.

Split the latter functionality out to be easier to understand.  This also
make it clear that we don't need to attach the rmap inode to a
transaction for the skipped blocks case as we never dirty any peristent
data structure.

Also make the argument order to xfs_zone_record_blocks a bit more
natural.

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