Update calls to IInterface::asBinder()

to use the new static version.

Change-Id: I89a5988a0ac694ffc04d88cf939e8455bf925d4c
diff --git a/drm/common/IDrmManagerService.cpp b/drm/common/IDrmManagerService.cpp
index 36cb612..3f62ed7 100644
--- a/drm/common/IDrmManagerService.cpp
+++ b/drm/common/IDrmManagerService.cpp
@@ -148,8 +148,7 @@
 
     data.writeInterfaceToken(IDrmManagerService::getInterfaceDescriptor());
     data.writeInt32(uniqueId);
-    data.writeStrongBinder(
-        drmServiceListener != NULL ? drmServiceListener->asBinder() : NULL);
+    data.writeStrongBinder(IInterface::asBinder(drmServiceListener));
     remote()->transact(SET_DRM_SERVICE_LISTENER, data, &reply);
     return reply.readInt32();
 }