crypto: skcipher - remove crypto_skcipher::decrypt

Due to the removal of the blkcipher and ablkcipher algorithm types,
crypto_skcipher::decrypt is now redundant since it always equals
crypto_skcipher_alg(tfm)->decrypt.

Remove it and update crypto_skcipher_decrypt() accordingly.

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

include/crypto/skcipher.h

@@ -35,8 +35,6 @@ struct skcipher_request {
 };
 
 struct crypto_skcipher {
-	int (*decrypt)(struct skcipher_request *req);
-
 	unsigned int reqsize;
 
 	struct crypto_tfm base;