leds: max77650: add MODULE_ALIAS()

Define a MODULE_ALIAS() in the LED sub-driver for max77650 so that
the appropriate module gets loaded together with the core mfd driver.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>