Add subsystem name field to Channel

Bug: 178115561
Test: atest FrameworksServicesTests:PowerStatsServiceTest
Change-Id: I864d9ff729534d81a1f7a89c860a78d659ccc1b2
diff --git a/tools/powerstats/PowerStatsServiceProtoParser.java b/tools/powerstats/PowerStatsServiceProtoParser.java
index e4135b5..2140954 100644
--- a/tools/powerstats/PowerStatsServiceProtoParser.java
+++ b/tools/powerstats/PowerStatsServiceProtoParser.java
@@ -30,7 +30,7 @@
         for (int i = 0; i < proto.getChannelCount(); i++) {
             ChannelProto energyMeterInfo = proto.getChannel(i);
             csvHeader += "Index,Timestamp,Duration," + energyMeterInfo.getId()
-                + "/" + energyMeterInfo.getName() + ",";
+                + "/" + energyMeterInfo.getName() + "/" + energyMeterInfo.getSubsystem() + ",";
         }
         System.out.println(csvHeader);
     }