arm64: dts: rockchip: Rename LED related pinctrl nodes on rk3308-rock-pi-s

The nodename, <name>-gpio, of referenced pinctrl nodes for the two LEDs
on the ROCK Pi S cause DT schema validation error:

  leds: green-led-gpio: {'rockchip,pins': [[0, 6, 0, 90]], 'phandle': [[98]]} is not of type 'array'
        from schema $id: http://devicetree.org/schemas/gpio/gpio-consumer.yaml#
  leds: heartbeat-led-gpio: {'rockchip,pins': [[0, 5, 0, 90]], 'phandle': [[99]]} is not of type 'array'
        from schema $id: http://devicetree.org/schemas/gpio/gpio-consumer.yaml#

Rename the pinctrl nodes and symbols to pass DT schema validation, also
extend LED nodes with information about color and function.

Fixes: 2e04c25b

 ("arm64: dts: rockchip: add ROCK Pi S DTS support")
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Link: https://lore.kernel.org/r/20240521211029.1236094-7-jonas@kwiboo.se
Signed-off-by: Heiko Stuebner <heiko@sntech.de>