net: sched: act_pedit: remove dependency on rtnl lock

Rearrange pedit init code to only access pedit action data while holding
tcf spinlock. Change keys allocation type to atomic to allow it to execute
while holding tcf spinlock. Take tcf spinlock in dump function when
accessing pedit action data.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>