Merge pull request #10783 from kaspar030/fix_native_timer

cpu/native/periph/timer: fix type conversion

cpu/native/periph/timer.c

@@ -66,7 +66,7 @@ static struct itimerval itv;
 static unsigned long ts2ticks(struct timespec *tp)
 {
     /* TODO: check for overflow */
-    return((tp->tv_sec * NATIVE_TIMER_SPEED) + (tp->tv_nsec / 1000));
+    return(((unsigned long)tp->tv_sec * NATIVE_TIMER_SPEED) + (tp->tv_nsec / 1000));
 }
 
 /**