update uffs filesystem read access error.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1638 bbd45198-f89e-11dd-88c7-29a3b14d5316

components/dfs/filesystems/uffs/dfs_uffs.c

@@ -174,7 +174,7 @@ int dfs_uffs_read(struct dfs_fd* fd, void* buf, rt_size_t count)
 	RT_ASSERT(fd != RT_NULL);
 
 	/* update position */
-	fp->pos  = fd->pos;
+	fd->pos  = fp->pos;
 
 	return uffs_ReadObject(fp, buf, count);  
 }