powerstats: correct frequency unit

Bug: 192579762
Test: dumpsys android.hardware.power.stats.IPowerStats/default
Change-Id: I8f7703c30116622483faa55f9dc16a5558d43c08
diff --git a/powerstats/DevfreqStateResidencyDataProvider.cpp b/powerstats/DevfreqStateResidencyDataProvider.cpp
index 9b21b88..d59e1e5 100644
--- a/powerstats/DevfreqStateResidencyDataProvider.cpp
+++ b/powerstats/DevfreqStateResidencyDataProvider.cpp
@@ -97,7 +97,7 @@
     int32_t id = 0;
     std::vector<State> states;
     for (const auto[frequencyHz, totalTimeMs] : timeInState) {
-        State s = {.id = id++, .name = std::to_string(frequencyHz / 1000) + "KHz"};
+        State s = {.id = id++, .name = std::to_string(frequencyHz / 1000) + "MHz"};
         states.push_back(s);
     }