crypto: s390/aes - drop redundant xts key check

xts_fallback_setkey() in xts_aes_set_key() will now enforce key size
rule in FIPS mode when setting up the fallback algorithm keys, which
makes the check in xts_aes_set_key() redundant or unreachable. So just
drop this check.

xts_fallback_setkey() now makes a key size check in xts_verify_key():

xts_fallback_setkey()
  crypto_skcipher_setkey() [ skcipher_setkey_unaligned() ]
    cipher->setkey() { .setkey = xts_setkey }
      xts_setkey()
        xts_verify_key()
Signed-off-by: NVladis Dronov <vdronov@redhat.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

arch/s390/crypto/aes_s390.c

@@ -398,10 +398,6 @@ static int xts_aes_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
 	if (err)
 		return err;
 
-	/* In fips mode only 128 bit or 256 bit keys are valid */
-	if (fips_enabled && key_len != 32 && key_len != 64)
-		return -EINVAL;
-
 	/* Pick the correct function code based on the key length */
 	fc = (key_len == 32) ? CPACF_KM_XTS_128 :
 	     (key_len == 64) ? CPACF_KM_XTS_256 : 0;