net: reduce net_rx_action() latency to 2 HZ

We should use time_after_eq() to get maximum latency of two ticks,
instead of three.

Bug added in commit 24f8b238

 (net: increase receive packet quantum)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>