Fixing format for log messages

code_cleanup_batching for EQL driver
Follow log essage format for i18n - http://docs.openstack.org/developer/oslo.i18n/guidelines.html#adding-variables-to-log-messages

Closes-Bug: 1362337

Change-Id: Ic3726f725efa4d29204e8530a8f191b801a4aac8