net/mlx4: Move the tunnel steering helper function to mlx4_core

Move the function which we use to set VXLAN DMFS (flow-steering) rules
from mlx4_en to mlx4_core. This refactoring will allow the mlx4_ib driver
to call the helper for the use case of user-space RAW Ethernet QPs, such
that they can serve VXLAN traffic too.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ethernet/mellanox/mlx4/en_netdev.c
Simple merge

diff --cc drivers/net/ethernet/mellanox/mlx4/mcg.c
Simple merge

diff --cc include/linux/mlx4/device.h
Simple merge