add exfat config

components/dfs/Kconfig

@@ -150,8 +150,8 @@ endif
             depends on RT_DFS_ELM_REENTRANT
 
         config RT_DFS_ELM_USE_EXFAT
-        bool "Enable RT_DFS_ELM_USE_EXFAT"
-        default n
+            bool "Enable RT_DFS_ELM_USE_EXFAT"
+            default n
         endmenu
     endif