net/mlx5_core: Set flow steering dest only for forward rules

We need to handle flow table entry destinations only if the action
associated with the rule is forwarding (MLX5_FLOW_CONTEXT_ACTION_FWD_DEST).

Fixes: 26a81453

 ('net/mlx5_core: Introduce flow steering firmware commands')
Signed-off-by: Amir Vadai <amir@vadai.me>
Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>