Change group owner of Bluetooth sleep node to net_bt_stack

This will enable lpm support for multi-user mode for tilapia
bug 7347413

Change-Id: I4b5877e9484a9aaad4546ebb434b296833e3d363
diff --git a/init.tilapia.rc b/init.tilapia.rc
index 4f33589..431b0e4 100644
--- a/init.tilapia.rc
+++ b/init.tilapia.rc
@@ -69,8 +69,8 @@
     # bluetooth LPM
     chmod 0220 /proc/bluetooth/sleep/lpm
     chmod 0220 /proc/bluetooth/sleep/btwrite
-    chown bluetooth bluetooth /proc/bluetooth/sleep/lpm
-    chown bluetooth bluetooth /proc/bluetooth/sleep/btwrite
+    chown bluetooth net_bt_stack /proc/bluetooth/sleep/lpm
+    chown bluetooth net_bt_stack /proc/bluetooth/sleep/btwrite
 
 # NFC
     setprop ro.nfc.port "I2C"