unselect PNET_USING_RAMFS

Author: kurisaW

iot/p-net/Kconfig

@@ -2,7 +2,6 @@ menuconfig PKG_USING_PNET
     bool "P-Net stack for Profinet device implementation"
     select BSP_USING_ETH
     select RT_LWIP_SNMP
-    select PNET_USING_RAMFS
     select PKG_PENT_NETIF_NAME
     select PKG_PNET_BOARD_CONFIG
     select PKG_PENT_FILESYSTEM_CONFIG
@@ -41,10 +40,10 @@ if PKG_USING_PNET
         default n
         if PKG_PENT_FILESYSTEM_CONFIG
             config PNET_USING_RAMFS
-                string "p-net using ramfs filesystem by default, or you can turn this off and choose another way to enable the filesystem"
+                bool "p-net using ramfs filesystem by default, or you can turn this off and choose another way to enable the filesystem"
                 select RT_USING_DFS
                 select RT_USING_DFS_RAMFS
-                default y
+                default n
 
             config APP_DEFAULT_FILE_DIRECTORY
                 string "p-net app default file directory, default as '/'"