Make sure processHalResult moves the value correctly

Bug: 317387260
Test: atest libpowermanager_test libsurfaceflinger_unittest libcompositionengine_test
Change-Id: I96560e3c01c79401d7bdbe828f603d760baab5f2
diff --git a/services/powermanager/PowerHalController.cpp b/services/powermanager/PowerHalController.cpp
index c049d7d..bc178bc 100644
--- a/services/powermanager/PowerHalController.cpp
+++ b/services/powermanager/PowerHalController.cpp
@@ -88,7 +88,7 @@
         mConnectedHal = nullptr;
         mHalConnector->reset();
     }
-    return result;
+    return std::move(result);
 }
 
 HalResult<void> PowerHalController::setBoost(aidl::android::hardware::power::Boost boost,