Fix missed '_' import
Fix missed '_' import

This patch fixes missed import of '_' in
ironic/api/controllers/v1/drivers.py

Change-Id: Ie076000b441ada7f45aff26e96fe627a961f7336
Related-Bug: #1524745

pshchelo/ironic,openstack/ironic,SauloAislan/ironic,SauloAislan/ironic,NaohiroTamura/ironic,NaohiroTamura/ironic,openstack/ironic,pshchelo/ironic