Preload2: Fix object to sync on

When moving to sync on the right objects, these waits() have been
forgotten.

Change-Id: I61b0d3c5cc41b7f46fbdd3099ec44221e653001a

tools/preload2/src/com/android/preload/DeviceUtils.java

@@ -285,7 +285,7 @@ public class DeviceUtils {
 
               if (device == null) {
                   try {
-                      wait(timeout);
+                      wfdl.wait(timeout);
                   } catch (InterruptedException e) {
                       // Ignore spurious wakeups.
                   }
@@ -304,7 +304,7 @@ public class DeviceUtils {
 
               if (!device.hasClients()) {
                   try {
-                      wait(timeout);
+                      wfcl.wait(timeout);
                   } catch (InterruptedException e) {
                       // Ignore spurious wakeups.
                   }