net/mlx5: LAG, introduce software vport LAG implementation

net/mlx5: LAG, introduce software vport LAG implementation

SD LAG is a virtual LAG without hardware LAG support, so it cannot use
the firmware vport LAG commands. Implement a software-based vport LAG
using egress ACL bounce rules.

Add esw_set_slave_egress_rule() to create an egress ACL rule on the
slave's manager vport that bounces traffic to the master's manager
vport. This achieves the same traffic steering as hardware vport LAG.

Redirect mlx5_cmd_create_vport_lag() and mlx5_cmd_destroy_vport_lag()
to the software implementation when operating in SD LAG mode.
In addition, adjust lag_demux creation to check SD LAG mode as well.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20260612113904.537595-12-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>