To remove drm service from groups of "system" and "root".

Change-Id: Ieac11c667c72465f7082baab0787dc740797049f
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 9f3020f..f230965 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -374,7 +374,7 @@
 service drm /system/bin/drmserver
     class main
     user drm
-    group system root inet
+    group inet
 
 service drmio /system/bin/drmioserver
     class main