iomap: add a bioset pointer to iomap_read_folio_ops

iomap: add a bioset pointer to iomap_read_folio_ops

Optionally allocate the bio from the bioset provided in
iomap_read_folio_ops.  If no bioset is provided, fs_bio_set is still
used, which is the standard bioset for file systems.

Based on a patch from Goldwyn Rodrigues <rgoldwyn@suse.com>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260223132021.292832-14-hch@lst.de
Tested-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>