add system group to netmgrd process

To allow netmgrd to acquire wakelocks correctly
we need to ensure that it belongs to system group

Bug: 24546055

Change-Id: I00b9effa7351f1cd8ef9fc062de12b5276254801
diff --git a/init.angler.rc b/init.angler.rc
index 6ac92c2..07a59d8 100755
--- a/init.angler.rc
+++ b/init.angler.rc
@@ -298,7 +298,7 @@
 
 service netmgrd /system/bin/netmgrd
     class main
-    group radio
+    group radio system
 
 service qti /system/vendor/bin/qti
     class main