crypto: ahash - Remove old_ahash_alg

Now that all ahash implementations have been converted to the new
ahash type, we can remove old_ahash_alg and its associated support.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/hash.h b/include/crypto/hash.h
index 262861d..45c2bdd 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h
@@ -89,7 +89,6 @@
 	int (*setkey)(struct crypto_ahash *tfm, const u8 *key,
 		      unsigned int keylen);
 
-	unsigned int digestsize;
 	unsigned int reqsize;
 	struct crypto_tfm base;
 };
@@ -137,7 +136,7 @@
 
 static inline unsigned int crypto_ahash_digestsize(struct crypto_ahash *tfm)
 {
-	return tfm->digestsize;
+	return crypto_hash_alg_common(tfm)->digestsize;
 }
 
 static inline unsigned int crypto_ahash_statesize(struct crypto_ahash *tfm)