leds: gpio: Configure per-LED pin control

Each gpio-leds DT node DT subnode can have a pinctrl property assigned
to it, parse the DT subnode pinctrl properties and configure each pin
accordingly.

Tested-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20230523183151.5460-1-marex@denx.de


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