[BRIDGE]: Round off STP perodic timers.

Peroidic STP timers don't have to be exact.  The hold timer runs at
1HZ, and the hello timer normally runs at 2HZ; save power by aligning
it them to next second.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_stp.c

@@ -178,7 +178,8 @@ void br_transmit_config(struct net_bridge_port *p)
 		br_send_config_bpdu(p, &bpdu);
 		p->topology_change_ack = 0;
 		p->config_pending = 0;
-		mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME);
+		mod_timer(&p->hold_timer,
+			  round_jiffies(jiffies + BR_HOLD_TIME));
 	}
 }
 

net/bridge/br_stp_timer.c

@@ -42,7 +42,7 @@ static void br_hello_timer_expired(unsigned long arg)
 	if (br->dev->flags & IFF_UP) {
 		br_config_bpdu_generation(br);
 
-		mod_timer(&br->hello_timer, jiffies + br->hello_time);
+		mod_timer(&br->hello_timer, round_jiffies(jiffies + br->hello_time));
 	}
 	spin_unlock(&br->lock);
 }