4823 don't open-code NSEC2MSEC and MSEC2NSEC

@@ -354,11 +354,11 @@
         } else {
                 delay = busy->delays[busy->delay_size - 1];
         }
         busy->total += delay;
         rqtp.tv_sec = 0;
-        rqtp.tv_nsec = delay * (NANOSEC / MILLISEC);
+        rqtp.tv_nsec = MSEC2NSEC(delay);
         (void) nanosleep(&rqtp, NULL);
         return (1);
 }