devlink: add port to line card relationship set

In order to properly inform user about relationship between port and
line card, introduce a driver API to set line card for a port. Use this
information to extend port devlink netlink message by line card index
and also include the line card index into phys_port_name and by that
into a netdevice name.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>