net/vhost: prevent multiple setups on reconfiguration

net/vhost: prevent multiple setups on reconfiguration

Ethdev's .dev_configure callback can be called multiple
time during a device life-time, but Vhost makes the
wrong assumption that it is not the case and try to
setup again the device on reconfiguration.

This patch ensures the device hasn't been already setup
before proceeding.

Fixes: 3d01b759d267 ("net/vhost: delay driver setup")
Cc: stable@dpdk.org
Reported-by: Yinan Wang <yinan.wang@intel.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Tested-by: Yinan Wang <yinan.wang@intel.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>
Reviewed-by: Tiwei Bie <tiwei.bie@intel.com>