4823 don't open-code NSEC2MSEC and MSEC2NSEC

*** 354,364 ****
          } else {
                  delay = busy->delays[busy->delay_size - 1];
          }
          busy->total += delay;
          rqtp.tv_sec = 0;
!         rqtp.tv_nsec = delay * (NANOSEC / MILLISEC);
          (void) nanosleep(&rqtp, NULL);
          return (1);
  }
  
  
--- 354,364 ----
          } else {
                  delay = busy->delays[busy->delay_size - 1];
          }
          busy->total += delay;
          rqtp.tv_sec = 0;
!         rqtp.tv_nsec = MSEC2NSEC(delay);
          (void) nanosleep(&rqtp, NULL);
          return (1);
  }