arm64: dts: rockchip: fix gmac support for NanoPi R5S

- Changed phy-mode to rgmii.

- Fixed pull type in pinctrl for gmac0.

- Removed duplicate properties in mdio node.
  These properties are defined in the gmac0 node already.

Signed-off-by: Tianling Shen <cnsztl@gmail.com>
Link: https://lore.kernel.org/r/20230318083745.6181-5-cnsztl@gmail.com


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