vm-virtio: Make all virtio devices potentially multi-threaded

Although only the block and net virtio devices can actually be multi
threaded (for now), handling them as special cases makes the code more
complex.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

vm-virtio/src/device.rs

@@ -137,7 +137,9 @@ macro_rules! virtio_pausable_inner {
             );
             self.paused.store(false, Ordering::SeqCst);
             if let Some(epoll_thread) = &self.epoll_thread {
-                epoll_thread.thread().unpark();
+                for i in 0..epoll_thread.len() {
+                    epoll_thread[i].thread().unpark();
+                }
             }
 
             Ok(())