arm64: dts: rockchip: Add phy-supply to gmac0 on NanoPi R5S

According to paragraph "7.16. Power" of the RTL8211F-CG datasheet, gmac0
needs to have a 3.3V power supply.
On page 22 of the NanoPi R5S version 2204, that is identified as
VCC_GEPHY_3V3 which is connected to the VCC_3V3 power source.

This fixes the following warning:

  rk_gmac-dwmac fe2a0000.ethernet: supply phy not found, using dummy regulator

Signed-off-by: Diederik de Haas <didi.debian@cknow.org>
Link: https://lore.kernel.org/r/20250503152917.138648-2-didi.debian@cknow.org


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