Misc CAL fixes

1. Regression in volume device type/bus checks
2. Handle model diffs in volume
3. Handle 'None' assignment to VDU params

Change-Id: Ia7c36cc583018d986b9bced49d5cf596b58ce94e
Signed-off-by: chamarty <ravi.chamarty@riftio.com>
1 file changed