4823 don't open-code NSEC2MSEC and MSEC2NSEC

*** 114,124 ****
   * Driver global variables
   */
  static void *power_state;
  static int power_inst = -1;
  
! static hrtime_t power_button_debounce = NANOSEC/MILLISEC*10;
  static hrtime_t power_button_abort_interval = 1.5 * NANOSEC;
  static int      power_button_abort_presses = 3;
  static int      power_button_abort_enable = 1;
  static int      power_button_enable = 1;
  
--- 114,124 ----
   * Driver global variables
   */
  static void *power_state;
  static int power_inst = -1;
  
! static hrtime_t power_button_debounce = MSEC2NSEC(10);
  static hrtime_t power_button_abort_interval = 1.5 * NANOSEC;
  static int      power_button_abort_presses = 3;
  static int      power_button_abort_enable = 1;
  static int      power_button_enable = 1;