powerstats: bring PixelStateResidencyDataProvider to device config

Second parameter is required to add PixelStateResidencyDataProvider.
If display entity name is empty, the device doesn't support display
VRR power stats.

Bug: 335379104
Test: dumpsys android.hardware.power.stats.IPowerStats/default
Change-Id: Id70ce01ef50a56d690c0942ae7e2ac2560abc435
Signed-off-by: Darren Hsu <darrenhsu@google.com>

powerstats/tegu/service.cpp

@@ -62,6 +62,7 @@ int main() {
 
     std::shared_ptr<PowerStats> p = ndk::SharedRefBase::make<PowerStats>();
 
+    addPixelStateResidencyDataProvider(p, "");
     addZumaProCommonDataProviders(p);
     addDisplay(p);