fixup! commands: add ubiformat

This adds the missing ubiformat.c file missing from:

commit 5a29d4aea71336558e13eb6ad8e662781653ae56
Author: Wolfram Sang <w.sang@pengutronix.de>
Date:   Mon Dec 17 16:48:33 2012 +0100

    commands: add ubiformat

    Imported from mtd-utils and stripped down to needed functionality.
    Based on an older version (1.4.5.) since the newer do use MEMWRITE
    interfaces which we don't have in barebox (yet).

    Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
    Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>