[BSP][STM32] 增加RT_USING_CPU_FFS配置选项

kconfig中增加RT_USING_CPU_FFS配置选项，并且默认开启

bsp/stm32/libraries/Kconfig

@@ -39,4 +39,8 @@ config SOC_SERIES_STM32G0
 config SOC_SERIES_STM32H7
     bool
     select ARCH_ARM_CORTEX_M7
-    select SOC_FAMILY_STM32
\ No newline at end of file
+    select SOC_FAMILY_STM32
+    
+config RT_USING_CPU_FFS
+    bool "Using CPU FFS"
+    default y