nvme-auth: host: remove allocation of crypto_shash

nvme-auth: host: remove allocation of crypto_shash

Now that the crypto_shash that is being allocated in
nvme_auth_process_dhchap_challenge() and stored in the
struct nvme_dhchap_queue_context is no longer used, remove it.

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>