pimd: fix missing the first round on wheel timer

`wheel_add_timer` will not *update* currrent wheel timer's wake-up time.
It means next wake-up time is set before this insertion, and can't be changed.
So added timers in this round between `current slot` and `nexttime slot`
will unluckily miss the current round.

Clearly it will lead to this problem:
You expect to be woken up within 30s, you maybe be woken up within 60s.
Yes, it is bad luck to miss the first round, but won't miss any more
rounds.

Coincidentally, pimd has one of the most important judgement for this
time. If missed the first round, pimd will miss all the world.

This fix is small and convervative. Just doubles the desired time interval.

pimd/pim_upstream.c

@@ -2025,10 +2025,10 @@ static bool pim_upstream_sg_running_proc(struct pim_upstream *up)
 
 	// Have we seen packets?
 	if ((up->channel_oil->cc.oldpktcnt >= up->channel_oil->cc.pktcnt)
-	    && (up->channel_oil->cc.lastused / 100 > 30)) {
+	    && (up->channel_oil->cc.lastused / 100 > 60)) {
 		if (PIM_DEBUG_PIM_TRACE) {
 			zlog_debug(
-				"%s[%s]: %s old packet count is equal or lastused is greater than 30, (%ld,%ld,%lld)",
+				"%s[%s]: %s old packet count is equal or lastused is greater than 60, (%ld,%ld,%lld)",
 				__func__, up->sg_str, pim->vrf->name,
 				up->channel_oil->cc.oldpktcnt,
 				up->channel_oil->cc.pktcnt,