md/raid0: convert raid0_make_request() to use bio_submit_split_bioset()

md/raid0: convert raid0_make_request() to use bio_submit_split_bioset()

Currently, raid0_make_request() will remap the original bio to underlying
disks to prevent reordered IO. Now that bio_submit_split_bioset() will put
original bio to the head of current->bio_list, it's safe converting to use
this helper and bio will still be ordered.

CC: Jan Kara <jack@suse.cz>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>