leds: bcm6358: merge bcm6358_led_mode and bcm6358_led_set

bcm6358_led_mode is now only called by bcm6358_led_set, so merge both
in one single function.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>