net: sched: make cls_u32 per cpu

This uses per cpu counters in cls_u32 in preparation
to convert over to rcu.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>