leds: triggers: don't depend on LEDS_TRIGGERS twice

All the triggers are defined in a big if LEDS_TRIGGERS...endif block.
So there is no need to let each driver depend on LEDS_TRIGGERS explicitly
once more.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>