btrfs: remove end_extent_writepage

end_extent_writepage is a small helper that combines a call to
btrfs_mark_ordered_io_finished with conditional error-only calls to
btrfs_page_clear_uptodate and mapping_set_error with a somewhat
unfortunate calling convention that passes and inclusive end instead
of the len expected by the underlying functions.

Remove end_extent_writepage and open code it in the 4 callers. Out
of those two already are error-only and thus don't need the extra
conditional, and one already has the mapping_set_error, so a duplicate
call can be avoided.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>