uboot-phytec

sandbox/fs: Use readdir instead of deprecated readdir_r

Using readdir_r limits the maximum file name length and may even be
unsafe, and is thus deprecated in since glibc 2.24.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Acked-by: Simon Glass <sjg@chromium.org>