Change group owner of Bluetooth sleep node to net_bt_stack

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

Change-Id: I3e51d0939b973dca9c74542bd43afef1e3c1262f
diff --git a/init.grouper.rc b/init.grouper.rc
index 591cc19..47ff2a0 100644
--- a/init.grouper.rc
+++ b/init.grouper.rc
@@ -64,8 +64,8 @@
     # 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"