arm64: dts: rockchip: Add RTC to Khadas Edge 2

Khadas Edge 2 has PT7C4363 RTC that compatible with HYM8563.
The RTC pinctrl is also connected to MCU.

Signed-off-by: Muhammed Efe Cetin <efectn@protonmail.com>
Link: https://lore.kernel.org/r/4c4c9140ff36f290ba64ecc8b3e218df6a5ab273.1708381247.git.efectn@protonmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>