Add missing header include for hw_ar3k

Add header include for hw_ar3k instead of relying on
include chain dependencies.

Change-Id: Ie0a43e07c670be8d8ab7174c910d062a87e9d82c
diff --git a/libbt-vendor/src/hw_ar3k.c b/libbt-vendor/src/hw_ar3k.c
index b1d50ab..cc54db8 100644
--- a/libbt-vendor/src/hw_ar3k.c
+++ b/libbt-vendor/src/hw_ar3k.c
@@ -50,6 +50,7 @@
 #include <string.h>
 
 #include "bt_hci_bdroid.h"
+#include "bt_vendor_qcom.h"
 #include "hci_uart.h"
 #include "hw_ar3k.h"