jfs: logmgr: use __bio_add_page to add single page to bio

jfs: logmgr: use __bio_add_page to add single page to bio

The JFS IO code uses bio_add_page() to add a page to a newly created bio.
bio_add_page() can fail, but the return value is never checked.

Use __bio_add_page() as adding a single page to a newly created bio is
guaranteed to succeed.

This brings us a step closer to marking bio_add_page() as __must_check.

Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/9fb5ed86d19f6e0b6f64dfc4109a48ff8ff24497.1685532726.git.johannes.thumshirn@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>