Make drmserver's primary group be system, so setgid is not required in ueventd.stingray.rc

Change-Id: Ie8a287620d22b5c1bdc459fb288b7403589ab474
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 8e08ef3..657797e 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -401,7 +401,7 @@
 service drm /system/bin/drmserver
     class main
     user drm
-    group inet system
+    group system inet
 
 service media /system/bin/mediaserver
     class main