cli: Add Busybox upstream hush.c file

This commit adds new file cli_hush_upstream.c, it is a copy of Busybox hush
file it was of time to Busybox commit 37460f5da.

Signed-off-by: Francis Laniel <francis.laniel@amarulasolutions.com>
Reviewed-by: Simon Glass <sjg@chromium.org>