Support audio device for vz driver

[balajiv113]

Description

This is a follow up of #1526 for vz driver

[afbjorklund]

Maybe we should add input/output as a configuration boolean ? Or always enable both, but could be surprising.

[afbjorklund]

BTW, virtio-sound is being worked on for qemu: https://wiki.qemu.org/Internships/ProjectIdeas/VirtioSound

[balajiv113]

My take would be based on device it could be enabled by default. If we need to add separate device for supporting both then its better to split with config.

Based on what QEMU supports, we can do similar configuration for VZ also