virtio: add support for tx-queue-size

virtio: add support for tx-queue-size

Type: improvement

DBGvpp# set loggin class virtio level debug
DBGvpp# create int virtio 0000:00:03.0 tx-queue-size 1024

show virtio pci
```
  Virtqueue (TX) 1
    qsz 1024, last_used_idx 0, desc_next 0, desc_in_use 0
    avail.flags 0x1 avail.idx 0 used.flags 0x0 used.idx 0
```

show logging
```
2022/07/22 23:20:22:557 debug      virtio         0000:00:03.0: tx-queue: number 1, default-size 256
2022/07/22 23:20:22:557 debug      virtio         0000:00:03.0: tx-queue: number 1, new size 1024
```

Change-Id: Ib1a3ebe742b3a6c9fe72bd1c5accfe07682cbdd1
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>