crypto: caam - avoid needlessly saving and restoring caam_hash_ctx

When exporting and importing the hash state, we will only export and
import into hashes which share the same struct crypto_ahash pointer.
(See hash_accept->af_alg_accept->hash_accept_parent.)

This means that saving the caam_hash_ctx structure on export, and
restoring it on import is a waste of resources.  So, remove this code.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>