fix gd32 dist bug

Author: CYFS3

bsp/gd32/arm/gd32527I-eval/board/Kconfig

@@ -380,7 +380,7 @@ menu "On-chip Peripheral Drivers"
         select RT_USING_SDRAM
         default n
 
-    rsource "../../libraries/gd32_drivers/Kconfig"
+    source "$(BSP_DIR)/../libraries/gd32_drivers/Kconfig"
 
 endmenu