RBD: Add missing driver options
RBD: Add missing driver options

The RBD driver was missing some of its configuration options in the
`get_driver_options` method returned list.

This patch adds those missing configuration options.

Change-Id: Ifdd2d54ba22d4fdc68be7d39f6f13cd543755df2

mahak/cinder,openstack/cinder,openstack/cinder,mahak/cinder