i40e: add reset to tx queue

i40e_bm/i40e_bm.h

@@ -230,6 +230,7 @@ class lan_queue_tx : public lan_queue_base {
         lan_queue_tx(lan &lanmgr_, uint32_t &reg_tail, size_t idx,
                 uint32_t &reg_ena, uint32_t &fpm_basereg,
                 uint32_t &reg_intqctl);
+        virtual void reset();
 };
 
 class lan_queue_rx : public lan_queue_base {

i40e_bm/i40e_lan.cc

@@ -276,11 +276,17 @@ void lan_queue_rx::packet_received(const void *data, size_t pktlen)
 lan_queue_tx::lan_queue_tx(lan &lanmgr_, uint32_t &reg_tail_, size_t idx_,
         uint32_t &reg_ena_, uint32_t &reg_fpmbase_, uint32_t &reg_intqctl)
     : lan_queue_base(lanmgr_, reg_tail_, idx_, reg_ena_, reg_fpmbase_,
-            reg_intqctl, 128)
+            reg_intqctl, 128), pktbuf_len(0)
 {
     desc_len = 16;
 }
 
+void lan_queue_tx::reset()
+{
+    pktbuf_len = 0;
+    queue_base::reset();
+}
+
 void lan_queue_tx::initialize()
 {
     std::cerr << "lan_queue_tx::initialize()" << std::endl;