net/mlx4: Fix uninitialized fields in rule when adding promiscuous mode to device managed flow steering

In procedure mlx4_flow_steer_promisc_add(), several fields
were left uninitialized in the rule structure.
Correctly initialize these fields.

Fixes: 592e49dd ("net/mlx4: Implement promiscuous mode with device managed flow-steering")
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>