Add default health 2.1 service to class charger

... so that it starts up in charger mode.

Test: boot charger and look at serial log
Bug: 142674987
Change-Id: Ic535b86840df1408b76e556f942aebdd9aaba111
diff --git a/health/2.1/default/android.hardware.health@2.1-service.rc b/health/2.1/default/android.hardware.health@2.1-service.rc
index 917f1c2..b6d9e3b 100644
--- a/health/2.1/default/android.hardware.health@2.1-service.rc
+++ b/health/2.1/default/android.hardware.health@2.1-service.rc
@@ -1,5 +1,5 @@
 service health-hal-2-1 /vendor/bin/hw/android.hardware.health@2.1-service
-    class hal
+    class hal charger
     user system
     group system
     capabilities WAKE_ALARM