dm-integrity: use the nop integrity profile

dm-integrity: use the nop integrity profile

Use the block layer built-in nop profile instead of reinventing it.

Tested by:

$ dd if=/dev/urandom of=key.bin bs=512 count=1

$ cryptsetup luksFormat -q --type luks2 --integrity hmac-sha256 \
 	--integrity-no-wipe /dev/nvme0n1 key.bin
$ cryptsetup luksOpen /dev/nvme0n1 luks-integrity --key-file key.bin

and then doing mkfs.xfs and simple I/O on the mount file system.

Signed-off-by: Christoph Hellwig <hch@lst.de>