[fdb]cli: fdb entries are cleared according to vlan or port or vlan&&port (sonic-net#657)

Fdb entries can be deleted with user specifying vlan or port or vlan&&port.

Author: yangshp1987

scripts/fdbclear

@@ -42,10 +42,15 @@ def main():
 
     try:
         fdb = FdbClear()
-        if args.vlan is not None:
-            print("command not supported yet.")
+        if args.vlan is not None and args.port is not None:
+            fdb.send_notification("PORTVLAN", args.port+'|'+args.vlan)
+            print("Port {} + Vlan{} FDB entries are cleared.".format(args.port, args.vlan))
+        elif args.vlan is not None:
+            fdb.send_notification("VLAN", args.vlan)
+            print("Vlan{} FDB entries are cleared.".format(args.vlan))
         elif args.port is not None:
-            print("command not supported yet.")
+            fdb.send_notification("PORT", args.port)
+            print("Port {} FDB entries are cleared.".format(args.port))
         else:
             fdb.send_notification("ALL", "ALL")
             print("FDB entries are cleared.")