add exfat config

components/dfs/Kconfig

@@ -164,6 +164,10 @@ endif
         default n
         # select PKG_USING_ZLIB
 
+    config RT_DFS_ELM_USE_EXFAT
+        bool "Enable RT_DFS_ELM_USE_EXFAT"
+        default n
+
 if RT_USING_DFS_V1
     config RT_USING_DFS_RAMFS
         bool "Enable RAM file system"