{net/RDMA}/mlx5: Add LAG demux table API and vport demux rules

{net/RDMA}/mlx5: Add LAG demux table API and vport demux rules

Downstream patches will introduce SW-only LAG (e.g. shared_fdb without
HW LAG). In this mode the firmware cannot create the LAG demux table,
but vport demuxing is still required.

Move LAG demux flow-table ownership to the LAG layer and introduce APIs
to init/cleanup the demux table and add/delete per-vport rules. Adjust
the RDMA driver to use the new APIs.

In this mode, the LAG layer will create a flow group that matches vport
metadata. Vports that are not native to the LAG master eswitch add the
demux rule during IB representor load and remove it on unload.
The demux rule forward traffic from said vports to their native eswitch
manager via a new dest type - MLX5_FLOW_DESTINATION_TYPE_VHCA_RX.

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/20260309093435.1850724-9-tariqt@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>