rte_eth_vhost_get_vid_from_port_id returns a value of 0 if
called before the first call to the new_device callback.
A vid value >=0 suggests the device is active which is not
the case in this instance. Initialise vid to a negative
value to prevent this.
Fixes: ee584e9710b9 ("vhost: add driver on top of the library")
Cc: stable@dpdk.org
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>