leds: pca963x: Add ACPI support

This patch enables ACPI support for leds-pca963x driver.

Signed-off-by: Tin Huynh <tnhuynh@apm.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>