Support per-sector NVMe metadata in dm-crypt.

This commit changes dm-crypt, so that it can use NVMe metadata to store
authentication information. We can put dm-crypt directly on the top of
NVMe device, without using dm-integrity.

This commit improves write throughput twice, becase the will be no writes
to the dm-integrity journal.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>