net/mlx4: Don't disable vxlan offloads under DMFS-A0 optimized steering

Except for VXLAN steering rules, all offloads should work as they were
under plain DMFS mode. Fix that by enabling all the offloads under
DMFS-A0 mode, except for VXLAN steering rules.

Fixes: d57febe1 "net/mlx4: Add A0 hybrid steering"
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>