Arranging name of gateway parameter

The patch changes gateway to gateway_ip parameter in reclass to be
set properly during subnet creation by neuton.client state.
https://github.com/salt-formulas/salt-formula-neutron/blob/master/neutron/client.sls#L94

Change-Id: Ic5c0249456e891bf519c49852d2c818626a23025
Related-PROD: PROD-19395
1 file changed