<fix>[vm]: fix the failure to start after disabling virtio for other types of vm
<fix>[vm]: fix the failure to start after disabling virtio for other types of vm

when the type of disk is drive, the value of unit uses
deviceAddress.unit

fixed memBalloonInfo undefined issue

Resolves: ZSTAC-48860

Change-Id: I6a6f6f79488603736f72756b616e69726172706b

zstackio/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility