vm-virtio: Rename epoll_thread to epoll_threads

Now that we unified epoll_thread to potentially be a vector of threads,
it makes sense to make it a plural field.

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

vm-virtio/src/console.rs

@@ -351,7 +351,7 @@ pub struct Console {
     out: Arc<Mutex<Box<dyn io::Write + Send + Sync + 'static>>>,
     queue_evts: Option<Vec<EventFd>>,
     interrupt_cb: Option<Arc<dyn VirtioInterrupt>>,
-    epoll_thread: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
+    epoll_threads: Option<Vec<thread::JoinHandle<result::Result<(), DeviceError>>>>,
     paused: Arc<AtomicBool>,
 }
 
@@ -391,7 +391,7 @@ impl Console {
                 out: Arc::new(Mutex::new(out)),
                 queue_evts: None,
                 interrupt_cb: None,
-                epoll_thread: None,
+                epoll_threads: None,
                 paused: Arc::new(AtomicBool::new(false)),
             },
             console_input,
@@ -554,7 +554,7 @@ impl VirtioDevice for Console {
                 ActivateError::BadActivate
             })?;
 
-        self.epoll_thread = Some(epoll_threads);
+        self.epoll_threads = Some(epoll_threads);
 
         Ok(())
     }