fs: iomap: use bio_add_folio_nofail where possible

When the iomap buffered-io code can't add a folio to a bio, it allocates a
new bio and adds the folio to that one. This is done using bio_add_folio(),
but doesn't check for errors.

As adding a folio to a newly created bio can't fail, use the newly
introduced bio_add_folio_nofail() function.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/58fa893c24c67340a63323f09a179fefdca07f2a.1685532726.git.johannes.thumshirn@wdc.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>