leds: simatic-ipc-leds-gpio: Add Elkhart Lake version

This is used for the Siemens Simatic IPC BX-21A, which has its LEDs
connected to GPIOs provided by the Intel Elkhart Lake pinctrl driver.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Link: https://lore.kernel.org/r/20230713115639.16419-3-henning.schild@siemens.com


Signed-off-by: Lee Jones <lee@kernel.org>