bio_alloc will never fail if it is allowed to sleep, so there is no
need for this loop.  Also remove the __GFP_HIGH specifier as it doesn't
make sense here given that we'll always fall back to the mempool anyway.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220124091107.642561-5-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>