KEYS: Merge the type-specific data with the payload data

Merge the type-specific data with the payload data into one four-word chunk
as it seems pointless to keep them separate.

Use user_key_payload() for accessing the payloads of overloaded
user-defined keys.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-cifs@vger.kernel.org
cc: ecryptfs@vger.kernel.org
cc: linux-ext4@vger.kernel.org
cc: linux-f2fs-devel@lists.sourceforge.net
cc: linux-nfs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: linux-ima-devel@lists.sourceforge.net
diff --git a/lib/digsig.c b/lib/digsig.c
index ae05ea39..07be6c1 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -79,12 +79,13 @@
 	unsigned char *out1 = NULL;
 	const char *m;
 	MPI in = NULL, res = NULL, pkey[2];
-	uint8_t *p, *datap, *endp;
-	struct user_key_payload *ukp;
+	uint8_t *p, *datap;
+	const uint8_t *endp;
+	const struct user_key_payload *ukp;
 	struct pubkey_hdr *pkh;
 
 	down_read(&key->sem);
-	ukp = key->payload.data;
+	ukp = user_key_payload(key);
 
 	if (ukp->datalen < sizeof(*pkh))
 		goto err1;