support for rlt-1600g-w and rlt-1600x-w in GPON mode

Change-Id: Ib230d3e336043980eb00427384a49cb8bd386bb2
diff --git a/agent/device/rlt-1600g-w/mkdebian/debian/rlt-1600g-w.install b/agent/device/rlt-1600g-w/mkdebian/debian/rlt-1600g-w.install
new file mode 100644
index 0000000..ceeb05b
--- /dev/null
+++ b/agent/device/rlt-1600g-w/mkdebian/debian/rlt-1600g-w.install
@@ -0,0 +1 @@
+/tmp