arm64: dts: meson-gxl: fix internal phy compatible

This fixes the following DT schemas check errors:
meson-gxl-s805x-libretech-ac.dt.yaml: ethernet-phy@8: compatible: ['ethernet-phy-id0181.4400', 'ethernet-phy-ieee802.3-c22'] is not valid under any of the given schemas

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>