[test][vmbase] Check VirtIO socket device in integration test

This cl checks the existence and number of VirtIO socket devices
in the vmbase integration test.

Bug: 284462758
Test: atest vmbase_example.integration_test
Change-Id: I69981f32964741a4258e621fb2254176cfeaae07
diff --git a/vmbase/src/virtio/pci.rs b/vmbase/src/virtio/pci.rs
index a75f0e2..1d05c18 100644
--- a/vmbase/src/virtio/pci.rs
+++ b/vmbase/src/virtio/pci.rs
@@ -22,7 +22,7 @@
 use log::debug;
 use once_cell::race::OnceBox;
 use virtio_drivers::{
-    device::blk,
+    device::{blk, socket},
     transport::pci::{
         bus::{BusDeviceIterator, PciRoot},
         virtio_device_type, PciTransport,
@@ -79,6 +79,11 @@
 /// Virtio Block device.
 pub type VirtIOBlk<T> = blk::VirtIOBlk<T, PciTransport>;
 
+/// Virtio Socket device.
+///
+/// Spec: https://docs.oasis-open.org/virtio/virtio/v1.2/csd01/virtio-v1.2-csd01.html 5.10
+pub type VirtIOSocket<T> = socket::VirtIOSocket<T, PciTransport>;
+
 /// An iterator that iterates over the PCI transport for each device.
 pub struct PciTransportIterator<'a, T: Hal> {
     pci_root: &'a mut PciRoot,