The attribute and variable `csiID` ise used for at least two different
things:
- name of the driver instance, used for journalling metadata
- objects of the CSIIdentifier struct, composing a volume-handle
By changing the name of the `csiID` attribute for driver instances to
`driverInstance`, any confusion should be prevented.
Signed-off-by: Niels de Vos <ndevos@ibm.com>
