flexvolume: make volume opts data match its usage
flexvolume: make volume opts data match its usage

1. Do not record unneeded cinder volume details.
2. Add missing fields that are in used.

Signed-off-by: Peng Tao <39d8af57313740070ea49547576f55682fe5221a@gmail.com>

resouer/frakti,resouer/frakti,resouer/frakti