crypto: authenc - 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/authenc.c

@@ -373,9 +373,9 @@ static int crypto_authenc_create(struct crypto_template *tmpl,
 	u32 mask;
 	struct aead_instance *inst;
 	struct authenc_instance_ctx *ctx;
+	struct skcipher_alg_common *enc;
 	struct hash_alg_common *auth;
 	struct crypto_alg *auth_base;
-	struct skcipher_alg *enc;
 	int err;
 
 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
@@ -398,7 +398,7 @@ static int crypto_authenc_create(struct crypto_template *tmpl,
 				   crypto_attr_alg_name(tb[2]), 0, mask);
 	if (err)
 		goto err_free_inst;
-	enc = crypto_spawn_skcipher_alg(&ctx->enc);
+	enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
 
 	ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
 			    auth_base->cra_alignmask + 1);
@@ -422,8 +422,8 @@ static int crypto_authenc_create(struct crypto_template *tmpl,
 				       enc->base.cra_alignmask;
 	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
 
-	inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
-	inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
+	inst->alg.ivsize = enc->ivsize;
+	inst->alg.chunksize = enc->chunksize;
 	inst->alg.maxauthsize = auth->digestsize;
 
 	inst->alg.init = crypto_authenc_init_tfm;