CLOUDSTACK-5661 [VMware] DetachIsoCmd succeeds even though cdrom is locked by VM as cdrom is mounted

DetachISO is succeeding even though detach opeartion is failing as cdrom is locked by VM as it was mounted inside VM.
Detect if cdrom is locked or not. If locked fail detach operation and warn user to unmount before detaching the iso/cdrom device.

Signed-off-by: Sateesh Chodapuneedi <sateesh@apache.org>