[bsp] [stm32] port to dfs

bsp/stm32/stm32f429-atk-apollo/applications/SConscript

@@ -7,6 +7,9 @@ src     = Split("""
 main.c
 """)
 
+if GetDepend(['RT_USING_DFS']):
+    src += ['mnt.c']
+
 group = DefineGroup('Applications', src, depend = [''], CPPPATH = CPPPATH)
 
 Return('group')

bsp/stm32/stm32f429-atk-apollo/applications/mnt.c

@@ -0,0 +1,20 @@
+#include <rtthread.h>
+
+#ifdef RT_USING_DFS
+#include <dfs_fs.h>
+
+int mnt_init(void)
+{
+    if (dfs_mount("W25Q256", "/", "elm", 0, 0) == 0)
+    {
+        rt_kprintf("W25Q256 mount successful!\n");
+    }
+    else
+    {
+        rt_kprintf("W25Q256 mount failed!\n");
+    }
+
+    return 0;
+}
+INIT_ENV_EXPORT(mnt_init);
+#endif