virtio: fix type for queue id

virtio: fix type for queue id

Changed vtpci_queue_idx type in function virtio_dev_queue_setup from
uint8_t to uint16_t to prevent possible data loss. Also changed type of
head variable in function virtio_send_command from uint32_t to uint16_t.

Variable rcv_cnt declared in function virtio_recv_mergeable_pkts was of
type uint32_t. It was used by virtqueue_dequeue_burst_rx function, which
expects argument of type uint16_t. Changed rcv_cnt variable type to
uint16_t to prevent possible data loss.

Issues found with static code analysis tool.

Signed-off-by: Maciej Gajdzica <maciejx.t.gajdzica@intel.com>
Acked-by: Changchun Ouyang <changchun.ouyang@intel.com>