Fix Hitachi HNAS Driver default helper
Fix Hitachi HNAS Driver default helper

Driver refator patch merged with incorrect default value
for helper config option which causes an error if the admin
does not set the config appropriately or leave it empty.

Change-Id: I48cb66d1b31abdf5e36f1b59a5f0cf52880d9951
Closes-bug: #1544974

NetApp/manila,openstack/manila,vponomaryov/manila,vponomaryov/manila,bswartz/manila,openstack/manila,NetApp/manila,bswartz/manila