Add missing build dependency

Change-Id: I62b589864200a8a79f9be848efd63866d299327c
diff --git a/debian/control b/debian/control
index 6642fe1..622de75 100644
--- a/debian/control
+++ b/debian/control
@@ -1,5 +1,6 @@
 Source: aiy-board-wlan
 Maintainer: AIY Projects <support-aiyprojects@google.com>
+Build-Depends: debhelper
 
 Package: aiy-board-wlan
 Section: net