leds: ktd2692: Fix a typo in the name of a constant

There is a typo in KTD2962_MM_MIN_CURR_THRESHOLD_SCALE. 6 and 9 are
switched in 2962.

Define and use KTD2692_MM_MIN_CURR_THRESHOLD_SCALE instead.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Enrico Weigelt <info@metux.net>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>