Remove default=None for configuration bindings

The default value for a configuration variable is None. There is
no need to specifically set these as None.

The line where this is done is:
https://github.com/openstack/oslo.config/blob/master/oslo_config/cfg.py#L684

TrivialFix

Change-Id: Iedf29b13d69ea9f2eb4d5aa746d7c1da8d83bafc
1 file changed
tree: f65e44781a2e6751b3496cf7414f2434f8740c3c
  1. neutron/