update comments to reflect new sig

synapse/api/auth.py

@@ -778,9 +778,6 @@ class Auth(object):
     def check_auth_blocking(self):
         """Checks if the user should be rejected for some external reason,
         such as monthly active user limiting or global disable flag
-        Args:
-            error (Error): The error that should be raised if user is to be
-            blocked
         """
         if self.hs.config.limit_usage_by_mau is True:
             current_mau = yield self.store.get_monthly_active_count()