net/mlx5: E-Switch, add logic to enable shared FDB

Shared FDB allows to direct traffic from all the vports in the HCA to a
single eswitch. In order to do that three things are needed.

1) Point the ingress ACL of the slave uplink to that of the master.
   With this, wire traffic from both uplinks will reach the same eswitch
   with the same metadata where a single steering rule can catch traffic
   from both ports.

2) Set the FDB root flow table of the slave's eswitch to that of the
   master. As this flow table can change dynamically make sure to
   sync it on any set root flow table FDB command.
   This will make sure traffic from SFs, VFs, ECPFs and PFs reach the
   master eswitch.

3) Split wire traffic at the eswitch manager egress ACL so that it's
   directed to the native eswitch manager. We only treat wire traffic
   from both ports the same at the eswitch level. If such traffic wasn't
   handled in the eswitch it needs to reach the right representor to be
   processed by software. For example LACP packets should *always*
   reach the right uplink representor for correct operation.

Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Mark Zhang <markzhang@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>