net/mlx5: Lag, decouple FDB selection and shared FDB

Multiport eswitch is required to use native FDB selection instead of
affinity, This was achieved by passing the shared_fdb flag down
the HW lag creation path. While it did accomplish the goal of setting
FDB selection mode to native, it had the side effect of also
creating a shared FDB configuration.

This created a few issues:
- TC rules are inserted into a non active FDB, which means traffic isn't
  offloaded as all traffic will reach only a single FDB.
- All wire traffic is treated as if a single physical port received it; while
  this is true for a bond configuration, this shouldn't be the case for
  multiport eswitch.

Create a new flag MLX5_LAG_MODE_FLAG_FDB_SEL_MODE_NATIVE
to indicate what FDB selection mode should be used.

Fixes: 94db3317 ("net/mlx5: Support multiport eswitch mode")
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>