crypto: skcipher - rename crypto_skcipher_type2 to crypto_skcipher_type

Now that the crypto_skcipher_type() function has been removed, there's
no reason to call the crypto_type struct for skciphers
"crypto_skcipher_type2".  Rename it to simply "crypto_skcipher_type".

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