libceph: don't pass result into ac->ops->handle_reply()

There is no result to pass in msgr2 case because authentication
failures are reported through auth_bad_method frame and in MAuth
case an error is returned immediately.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>