libceph: wrap auth ops in wrapper functions

Use wrapper functions that check whether the auth op exists so that callers
do not need a bunch of conditional checks.  Simplifies the external
interface.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
diff --git a/net/ceph/mon_client.c b/net/ceph/mon_client.c
index aef5b10..1fe25cd 100644
--- a/net/ceph/mon_client.c
+++ b/net/ceph/mon_client.c
@@ -737,7 +737,7 @@
 
 		__validate_auth(monc);
 
-		if (monc->auth->ops->is_authenticated(monc->auth))
+		if (ceph_auth_is_authenticated(monc->auth))
 			__send_subscribe(monc);
 	}
 	__schedule_delayed(monc);
@@ -892,8 +892,7 @@
 
 	mutex_lock(&monc->mutex);
 	had_debugfs_info = have_debugfs_info(monc);
-	if (monc->auth->ops)
-		was_auth = monc->auth->ops->is_authenticated(monc->auth);
+	was_auth = ceph_auth_is_authenticated(monc->auth);
 	monc->pending_auth = 0;
 	ret = ceph_handle_auth_reply(monc->auth, msg->front.iov_base,
 				     msg->front.iov_len,
@@ -904,7 +903,7 @@
 		wake_up_all(&monc->client->auth_wq);
 	} else if (ret > 0) {
 		__send_prepared_auth_request(monc, ret);
-	} else if (!was_auth && monc->auth->ops->is_authenticated(monc->auth)) {
+	} else if (!was_auth && ceph_auth_is_authenticated(monc->auth)) {
 		dout("authenticated, starting session\n");
 
 		monc->client->msgr.inst.name.type = CEPH_ENTITY_TYPE_CLIENT;