dragon: libbt: set BT_WAKE_USERIAL_LDISC = TRUE

Compile in Line Discipline support for BT power saving modes.

BUG: 25397536
Change-Id: If5c43835ae398a230ec846fe585f26705a806303
Signed-off-by: Myles Watson <mylesgw@google.com>
diff --git a/include/vnd_dragon.txt b/include/vnd_dragon.txt
index 1d601c1..55cd7e2 100644
--- a/include/vnd_dragon.txt
+++ b/include/vnd_dragon.txt
@@ -6,4 +6,5 @@
 VNDUSERIAL_DBG = FALSE
 BT_WAKE_VIA_PROC = FALSE
 BT_WAKE_VIA_USERIAL_IOCTL = TRUE
+BT_WAKE_USERIAL_LDISC = TRUE
 UPIO_DBG = FALSE