arm64: dts: rockchip: add gpio-line-names to radxa-zero-3

arm64: dts: rockchip: add gpio-line-names to radxa-zero-3

Add names to the pins of the general-purpose expansion header as given
in the Radxa documentation[1] following the conventions in the kernel[2]
to make it easier for users to correlate pins with functions when using
utilities such as 'gpioinfo'.

[1] https://docs.radxa.com/en/zero/zero3/hardware-design/hardware-interface
[2] https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Link: https://lore.kernel.org/r/20240620013301.33653-1-twoerner@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>