ubispl: migrate configuration to Kconfig

Move the ubispl configuration to KConfig and drop them from the
whitelist.

Signed-off-by: Markus Klotzbuecher <markus.klotzbuecher@kistler.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Javier Martínez Canillas <javier@dowhile0.org>
Cc: Enric Balletbo i Serra <eballetbo@gmail.com>