crypto: chacha20poly1305 - Only access common skcipher fields on spawn

As skcipher spawns may be of the type lskcipher, only the common
fields may be accessed.  This was already the case but use the
correct helpers to make this more obvious.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/chacha20poly1305.c

@@ -558,7 +558,7 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
 	u32 mask;
 	struct aead_instance *inst;
 	struct chachapoly_instance_ctx *ctx;
-	struct skcipher_alg *chacha;
+	struct skcipher_alg_common *chacha;
 	struct hash_alg_common *poly;
 	int err;
 
@@ -579,7 +579,7 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
 				   crypto_attr_alg_name(tb[1]), 0, mask);
 	if (err)
 		goto err_free_inst;
-	chacha = crypto_spawn_skcipher_alg(&ctx->chacha);
+	chacha = crypto_spawn_skcipher_alg_common(&ctx->chacha);
 
 	err = crypto_grab_ahash(&ctx->poly, aead_crypto_instance(inst),
 				crypto_attr_alg_name(tb[2]), 0, mask);
@@ -591,7 +591,7 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
 	if (poly->digestsize != POLY1305_DIGEST_SIZE)
 		goto err_free_inst;
 	/* Need 16-byte IV size, including Initial Block Counter value */
-	if (crypto_skcipher_alg_ivsize(chacha) != CHACHA_IV_SIZE)
+	if (chacha->ivsize != CHACHA_IV_SIZE)
 		goto err_free_inst;
 	/* Not a stream cipher? */
 	if (chacha->base.cra_blocksize != 1)
@@ -615,7 +615,7 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
 	inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
 				     ctx->saltlen;
 	inst->alg.ivsize = ivsize;
-	inst->alg.chunksize = crypto_skcipher_alg_chunksize(chacha);
+	inst->alg.chunksize = chacha->chunksize;
 	inst->alg.maxauthsize = POLY1305_DIGEST_SIZE;
 	inst->alg.init = chachapoly_init;
 	inst->alg.exit = chachapoly_exit;