crypto: s390/aes - convert to skcipher API

Convert the glue code for the S390 CPACF implementations of AES-ECB,
AES-CBC, AES-XTS, and AES-CTR from the deprecated "blkcipher" API to the
"skcipher" API.  This is needed in order for the blkcipher API to be
removed.

Note: I made CTR use the same function for encryption and decryption,
since CTR encryption and decryption are identical.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>