fs/vfs/fs_stat.c: fill file size for mtd inode

Now when stat() is calling for mtd device it also set size of file as number of bytes of all sectors related to this mtd device.

fs/vfs/fs_stat.c

@@ -46,6 +46,8 @@
 #include <errno.h>
 
 #include "inode/inode.h"
+#include <nuttx/mtd/mtd.h>
+#include <nuttx/fs/ioctl.h>
 
 /****************************************************************************
  * Pre-processor Definitions
@@ -303,6 +305,14 @@ int inode_stat(FAR struct inode *inode, FAR struct stat *buf)
           buf->st_mode  = S_IFMTD;
           buf->st_mode |= S_IROTH | S_IRGRP | S_IRUSR;
           buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR;
+
+          struct mtd_geometry_s mtdgeo;
+          if (inode->u.i_mtd
+                  && MTD_IOCTL(inode->u.i_mtd, MTDIOC_GEOMETRY,
+                          (unsigned long)((uintptr_t)&mtdgeo)) >= 0)
+            {
+              buf->st_size = mtdgeo.neraseblocks * mtdgeo.erasesize;
+            }
         }
       else
 #endif