Bluetooth: Update user group for smd channels

This patch updates the user group of smd channels to net_bt_stack.
Without this change, it was not possible for non root user to open
the smd channels resulting in Bluetooth not getting turned on and
resulting in crash in libbtvendor causing BT share to stop.
bug 15321227, 15402179

Change-Id: I92ced8c6b543bcad26637428193fe55470b205ec
diff --git a/ueventd.mako.rc b/ueventd.mako.rc
index b299e6b..f7ca672 100644
--- a/ueventd.mako.rc
+++ b/ueventd.mako.rc
@@ -1,5 +1,5 @@
-/dev/smd3                 0660   bluetooth  bluetooth
-/dev/smd2                 0660   bluetooth  bluetooth
+/dev/smd3                 0660   bluetooth  net_bt_stack
+/dev/smd2                 0660   bluetooth  net_bt_stack
 /dev/uinput               0660   system     bluetooth
 /dev/ttyHS0               0600   bluetooth  bluetooth
 /dev/ttyMSM0              0600   bluetooth  bluetooth