timer: use timerclear() rather than explicit tv_set = tv_usec = 0

Change-Id: I2735fc8d19fd68ef2c14a31e83cb396dc2e05587
diff --git a/src/timer.c b/src/timer.c
index 47d1786..a8cd42b 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -190,8 +190,7 @@
 			timersub(cand, current, &nearest);
 		else {
 			/* loop again inmediately */
-			nearest.tv_sec = 0;
-			nearest.tv_usec = 0;
+			timerclear(&nearest);
 		}
 		nearest_p = &nearest;
 	} else {