[CRYPTO] s390: Generic sha_update and sha_final

The sha_{update|final} functions are similar for every sha variant.
Since that is error-prone and redundant replace these functions by
a shared generic implementation for s390.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>