netdevsim: add all ports in nsim_dev_create() and del them in destroy()

Currently the probe/remove function does this separately. Put the
addition an deletion of ports into nsim_dev_create() and
nsim_dev_destroy().

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>