This patch adds a PCI wrapper device for the virtio-sound device.
It is necessary to instantiate a virtio-snd device in a guest.
All sound logic will be added to the virtio-snd device in the following
commits.

To add this device with a guest, you'll need a >=5.13 kernel compiled
with CONFIG_SND_VIRTIO=y, which at the time of writing most distros have
off by default.

Use with following flags in the invocation:

Pulseaudio:
  -audio driver=pa,model=virtio
  or
  -audio driver=pa,model=virtio,server=/run/user/1000/pulse/native
sdl:
  -audio driver=sdl,model=virtio
coreaudio (macos/darwin):
  -audio driver=coreaudio,model=virtio
etc.

Based-on: https://github.com/OpenSynergy/qemu/commit/5a2f350eec5d157b90d9c7b40a8e603f4da92471


Signed-off-by: Igor Skalkin <Igor.Skalkin@opensynergy.com>
Signed-off-by: Anton Yakovlev <Anton.Yakovlev@opensynergy.com>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <b223598d59f56ead6a6d8d9bb6801e17489ddaa4.1698062525.git.manos.pitsidianakis@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>