[CRYPTO] null: Add null blkcipher algorithm

This patch adds a null blkcipher algorithm called ecb(cipher_null) for
backwards compatibility.  Previously the null algorithm when used by
IPsec copied the data byte by byte.  This new algorithm optimises that
to a straight memcpy which lets us better measure inherent overheads in
our IPsec code.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/internal/skcipher.h

@@ -88,5 +88,10 @@ static inline void skcipher_givcrypt_complete(
 	ablkcipher_request_complete(&req->creq, err);
 }
 
+static inline u32 ablkcipher_request_flags(struct ablkcipher_request *req)
+{
+	return req->base.flags;
+}
+
 #endif	/* _CRYPTO_INTERNAL_SKCIPHER_H */