[SL-UP] : replace INCLUDE_vTaskDelayUntil with INCLUDE_xTaskDelayUntil. (#535)

Author: Sarthak-Shaha

examples/platform/silabs/FreeRTOSConfig.h

@@ -268,7 +268,7 @@ See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */
 #define INCLUDE_vTaskDelete (1)
 #define INCLUDE_vTaskSuspend (1)
 #define INCLUDE_xResumeFromISR (1)
-#define INCLUDE_vTaskDelayUntil (1)
+#define INCLUDE_xTaskDelayUntil (1)
 #define INCLUDE_vTaskDelay (1)
 #define INCLUDE_xTaskGetSchedulerState (1)
 #define INCLUDE_xTaskGetCurrentTaskHandle (1)