net/mlx5: E-Switch, Add control for inline mode

Implement devlink show and set of HW inline-mode.
The supported modes: none, link, network, transport.
We currently support one mode for all vports so set is done on all vports.
When eswitch is first initialized the inline-mode is queried from the FW.

Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>