Use RTEMS_SYSINIT_ORDER_LAST_BUT_5

Use RTEMS_SYSINIT_ORDER_LAST_BUT_5 instead of RTEMS_SYSINIT_ORDER_LAST
to allow applications and support functions to place system
initialization handlers behind the standard handlers.

Update #3838.

bsps/shared/dev/getentropy/getentropy-cpucounter.c

@@ -65,5 +65,5 @@ static void getentropy_init(void)
 RTEMS_SYSINIT_ITEM(
   getentropy_init,
   RTEMS_SYSINIT_DEVICE_DRIVERS,
-  RTEMS_SYSINIT_ORDER_LAST
+  RTEMS_SYSINIT_ORDER_LAST_BUT_5
 );