VOL-2188: Convert vlan id as uint32 otherwise type assertion fails

this prevents the downstream flow from being added.

Change-Id: I6f711569d7e63d589606e388ab3e0d444c9b5d1c
diff --git a/adaptercore/openolt_flowmgr.go b/adaptercore/openolt_flowmgr.go
index 900f442..9766484 100644
--- a/adaptercore/openolt_flowmgr.go
+++ b/adaptercore/openolt_flowmgr.go
@@ -551,7 +551,8 @@
 
 	/* Already this info available classifier? */
 	downlinkAction[PopVlan] = true
-	dlClVid, ok := downlinkClassifier[VlanVid].(int)
+	// vlan_vid is a uint32.  must be type asserted as such or conversion fails
+	dlClVid, ok := downlinkClassifier[VlanVid].(uint32)
 	if ok {
 		downlinkAction[VlanVid] = dlClVid & 0xfff
 	} else {