Update calls to IInterface::asBinder()

to use the new static version.

Change-Id: I89a5988a0ac694ffc04d88cf939e8455bf925d4c
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index e24832f..aef1844 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -396,7 +396,7 @@
     // do not lock the mutex in destructor
     releaseWakeLock_l();
     if (mPowerManager != 0) {
-        sp<IBinder> binder = mPowerManager->asBinder();
+        sp<IBinder> binder = IInterface::asBinder(mPowerManager);
         binder->unlinkToDeath(mDeathRecipient);
     }
 }