[BSP] [stm32f769-st-disco] fix error 'undefined reference to *entry*' after scons --menuconfig

bsp/stm32/stm32f769-st-disco/board/Kconfig

@@ -3,6 +3,8 @@ menu "Hardware Drivers Config"
 config SOC_STM32F769NI
     bool
     select SOC_SERIES_STM32F7
+    select RT_USING_COMPONENTS_INIT
+    select RT_USING_USER_MAIN
     default y
 
 menu "Onboard Peripheral Drivers"