pkcs7: use crypto_shash_digest()

Use crypto_shash_digest() instead of crypto_shash_init() followed by
crypto_shash_finup().  (For simplicity only; they are equivalent.)
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

crypto/asymmetric_keys/pkcs7_verify.c

@@ -59,11 +59,8 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
 	/* Digest the message [RFC2315 9.3] */
-	ret = crypto_shash_init(desc);
-	if (ret < 0)
-		goto error;
-	ret = crypto_shash_finup(desc, pkcs7->data, pkcs7->data_len,
-				 sig->digest);
+	ret = crypto_shash_digest(desc, pkcs7->data, pkcs7->data_len,
+				  sig->digest);
 	if (ret < 0)
 		goto error;
 	pr_devel("MsgDigest = [%*ph]\n", 8, sig->digest);