nvme-auth: common: use crypto library in nvme_auth_augmented_challenge()

nvme-auth: common: use crypto library in nvme_auth_augmented_challenge()

For the hash and HMAC computations in nvme_auth_augmented_challenge(),
use the crypto library instead of crypto_shash.  This is simpler,
faster, and more reliable.  Notably, this eliminates two crypto
transformation object allocations for every call, which was very slow.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Keith Busch <kbusch@kernel.org>