Use GID "wakelock" to control access to kernel wakelock

Bug: 25864142
Change-Id: I9c68defed9a47ddb33f70e73e29edcfa713da056
diff --git a/rild/rild.rc b/rild/rild.rc
index 0acbd20..35b424f 100644
--- a/rild/rild.rc
+++ b/rild/rild.rc
@@ -4,4 +4,4 @@
     socket sap_uim_socket1 stream 660 bluetooth bluetooth
     socket rild-debug stream 660 radio system
     user root
-    group radio cache inet misc audio log readproc
+    group radio cache inet misc audio log readproc wakelock