[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>
diff --git a/net/bridge/br_stp_timer.c b/net/bridge/br_stp_timer.c
index 24e0ca4..77f5255 100644
--- a/net/bridge/br_stp_timer.c
+++ b/net/bridge/br_stp_timer.c
@@ -42,7 +42,7 @@
 	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);
 }