leds: simatic-ipc-leds-gpio: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is (mostly) ignored
and this typically results in resource leaks. To improve here there is a
quest to make the remove callback return void. In the first step of this
quest all drivers are converted to .remove_new() which already returns
void.

Make simatic_ipc_leds_gpio_remove() return void instead of returning
zero unconditionally. After that the three remove callbacks that use
this function were trivial to convert to return void, too.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230916164516.1063380-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Lee Jones <lee@kernel.org>

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>

leds: simatic-ipc-leds-gpio: Split up into multiple drivers

In order to clearly describe the dependencies between the GPIO
controller drivers and the users the driver is split up into a core,
two drivers and a common header.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230524124628.32295-4-henning.schild@siemens.com