net/mlx5: E-Switch, Add definition of IB representor

Create a new representor type: REP_IB. which will be initialized by an IB
device that is used as a logical representor of a eswitch vport (VF or
uplink) just like we have a net device today in switchdev mode.

Signed-off-by: Mark Bloch <markb@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>