net/mlx5e: Remove TC header re-write offloading of ip tos

Currently the firmware API is partial and allows to offload only
the dscp part of the tos, also, ipv6 support isn't there yet.

As such, remove the offloading option of ipv4 dscp till the FW
APIs are more comprehensive.

Fixes: d79b6df6 ('net/mlx5e: Add parsing of TC pedit actions to HW format')
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>