crypto: skcipher - remove crypto_has_ablkcipher()

crypto_has_ablkcipher() has no users, and it does the same thing as
crypto_has_skcipher() anyway.  So remove it.  This also removes the last
user of crypto_skcipher_type() and crypto_skcipher_mask(), so remove
those too.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>