[DFS] fix the st_blksize issue in elm fatfs.

components/dfs/filesystems/elmfat/dfs_elm.c

@@ -27,6 +27,7 @@
  * 2013-03-01     aozima       fixed the stat(st_mtime) issue.
  * 2014-01-26     Bernard      Check the sector size before mount.
  * 2017-02-13     Hichard      Update Fatfs version to 0.12b, support exFAT.
+ * 2017-04-11     Bernard      fix the st_blksize issue.
  */
 
 #include <rtthread.h>
@@ -733,7 +734,6 @@ int dfs_elm_stat(struct dfs_filesystem *fs, const char *path, struct stat *st)
             st->st_mode &= ~(DFS_S_IWUSR | DFS_S_IWGRP | DFS_S_IWOTH);
 
         st->st_size  = file_info.fsize;
-        st->st_blksize = 512;
 
         /* get st_mtime. */
         {