virtio-pci: reset modern vq meta data

We don't reset proxy->vqs[].{num|desc[]|avail[]|used[]}. This means if
a driver enable the vq without setting vq address after reset. The old
addresses were leaked. Fixing this by resetting modern vq meta data
during device reset.

Cc: qemu-stable@nongnu.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>