vhost-user: save features of multiqueues if chardev is closed

vhost-user: save features of multiqueues if chardev is closed

Fore-commit(c6beefd674) only saves features of queue0,
this makes wrong features of other queues in multiqueues
situation.
For examples:
  qemu-system-aarch64 ... \
  -chardev socket,id=charnet0,path=/var/run/vhost_sock \
  -netdev vhost-user,chardev=charnet0,queues=2,id=hostnet0 \
  ...
There are two queues in nic assocated with one chardev.
When chardev is reconnected, it is necessary to save and
restore features of all queues.

Signed-of-by: Haibin Zhang <haibinzhang@tencent.com>
Message-Id: <46CBC206-E0CA-4249-81CD-10F75DA30441@tencent.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>