net sched actions: Use proper root attribute table for actions

Bug fix for an issue which has been around for about a decade.
We got away with it because the enumeration was larger than needed.

Fixes: 7ba699c6 ("[NET_SCHED]: Convert actions from rtnetlink to new netlink API")
Suggested-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>