xfs: simplify building the bio in xlog_write_iclog

Use the bio_add_virt_nofail and bio_add_vmalloc helpers to abstract
away the details of the memory allocation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20250507120451.4000627-18-hch@lst.de


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