net: cls_u32: move TC offload feature bit into cls_u32 offload logic

In the original series drivers would get offload requests for cls_u32
rules even if the feature bit is disabled. This meant the driver had
to do a boiler plate check on the feature bit before adding/deleting
the rule.

This patch lifts the check into the core code and removes it from the
driver specific case.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>