crypto: authenc - Use crypto_aead_set_reqsize helper

This patch uses the crypto_aead_set_reqsize helper to avoid directly
touching the internals of aead.

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

crypto/authenc.c

@@ -570,13 +570,14 @@ static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
 			    crypto_ahash_alignmask(auth) + 1) +
 		      crypto_ablkcipher_ivsize(enc);
 
-	tfm->crt_aead.reqsize = sizeof(struct authenc_request_ctx) +
-				ctx->reqoff +
-				max_t(unsigned int,
-				crypto_ahash_reqsize(auth) +
-				sizeof(struct ahash_request),
-				sizeof(struct skcipher_givcrypt_request) +
-				crypto_ablkcipher_reqsize(enc));
+	crypto_aead_set_reqsize(__crypto_aead_cast(tfm),
+		sizeof(struct authenc_request_ctx) +
+		ctx->reqoff +
+		max_t(unsigned int,
+			crypto_ahash_reqsize(auth) +
+			sizeof(struct ahash_request),
+			sizeof(struct skcipher_givcrypt_request) +
+			crypto_ablkcipher_reqsize(enc)));
 
 	return 0;