arm64: dts: rockchip: rename pinctrl nodename to gmac2io for nanopi-r2s board

arm64: dts: rockchip: rename pinctrl nodename to gmac2io for nanopi-r2s board

A test with the command below gives this error:
/arch/arm64/boot/dts/rockchip/rk3328-nanopi-r2s.dt.yaml:
ethernet-phy: 'reg' is a required property

The pinctrl nodename "ethernet-phy" conflicts with the rules
in the "ethernet-phy.yaml" document, so rename it to "gmac2io".

make ARCH=arm64 dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/net/ethernet-phy.yaml

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20210110194851.10207-1-jbx6244@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>