libceph: msg signing callouts don't need con argument

We can use msg->con instead - at the point we sign an outgoing message
or check the signature on the incoming one, msg->con is always set.  We
wouldn't know how to sign a message without an associated session (i.e.
msg->con == NULL) and being able to sign a message using an explicitly
provided authorizer is of no use.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index b2371d9..3687ff0 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -43,10 +43,9 @@
 	struct ceph_msg * (*alloc_msg) (struct ceph_connection *con,
 					struct ceph_msg_header *hdr,
 					int *skip);
-	int (*sign_message) (struct ceph_connection *con, struct ceph_msg *msg);
 
-	int (*check_message_signature) (struct ceph_connection *con,
-					struct ceph_msg *msg);
+	int (*sign_message) (struct ceph_msg *msg);
+	int (*check_message_signature) (struct ceph_msg *msg);
 };
 
 /* use format string %s%d */