busybox: fix CVE-2021-28831

Backport patch to fix CVE-2021-28831.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit e579dbd9)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>