net/virtio-user: fix not properly reset device

net/virtio-user: fix not properly reset device

virtio_user is not properly reset when users call vtpci_reset(),
as it ignores VIRTIO_CONFIG_STATUS_RESET status in
virtio_user_set_status().

This might lead to initialization failure as it starts to re-init
the device before sending RESET messege to backend. Besides, previous
callfds and kickfds are not closed.

To fix it, we add support to disable virtqueues when it's set to
DRIVER OK status, and re-init fields in struct virtio_user_dev.

Fixes: e9efa4d93821 ("net/virtio-user: add new virtual PCI driver")
Fixes: 37a7eb2ae816 ("net/virtio-user: add device emulation layer")
Cc: stable@dpdk.org
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>