net: replace ndo_get_devlink with ndo_get_devlink_port

Follow-up patch is going to need a devlink port instance according to
a netdev. Devlink port instance should be always available when devlink
is used. So change the recently introduced ndo_get_devlink to
ndo_get_devlink_port. With that, adjust the wrapper for the only
user to get devlink pointer.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>