tap: remove cxq_vring from tap/tun

Type: fix

virtio_if_t is shared data struct between tap, tun and virtio pci.
cxq_vring is virtio pci specific element. It shouldn't be set or
accessed in tap driver.

Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>
Change-Id: I8b34570f61b38d8b9d79d5b0669bda0f89ebc28c

src/vnet/devices/tap/tap.c

@@ -740,7 +740,6 @@ tap_create_if (vlib_main_t * vm, tap_create_if_args_t * args)
    * TUNSETCARRIER ioctl(). See tap_set_carrier().
    */
   vif->host_carrier_up = 1;
-  vif->cxq_vring = NULL;
 
   goto done;