There are three states for an ethdev port.
Checking that the port is unused looks simpler than
checking it is neither attached nor removed.
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
Tested-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>