net: sched: rename more stats_types

Commit 53eca1f3

 ("net: rename flow_action_hw_stats_types* ->
flow_action_hw_stats*") renamed just the flow action types and
helpers. For consistency rename variables, enums, struct members
and UAPI too (note that this UAPI was not in any official release,
yet).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>