igb: Read DCMD.VLE of the first Tx descriptor

Section 7.2.2.3 Advanced Transmit Data Descriptor says:
> For frames that spans multiple descriptors, all fields apart from
> DCMD.EOP, DCMD.RS, DCMD.DEXT, DTALEN, Address and DTYP are valid only
> in the first descriptors and are ignored in the subsequent ones.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/igb_core.c

@@ -613,7 +613,7 @@ igb_process_tx_desc(IGBCore *core,
             idx = (tx->first_olinfo_status >> 4) & 1;
             igb_tx_insert_vlan(core, queue_index, tx,
                 tx->ctx[idx].vlan_macip_lens >> 16,
-                !!(cmd_type_len & E1000_TXD_CMD_VLE));
+                !!(tx->first_cmd_type_len & E1000_TXD_CMD_VLE));
 
             if (igb_tx_pkt_send(core, tx, queue_index)) {
                 igb_on_tx_done_update_stats(core, tx->tx_pkt, queue_index);