arm64: dts: amlogic: meson-gxl: add missing unit address to eth-phy-mux node name

Fixes:
bus@c8834000: eth-phy-mux: {...} should not be valid under {'type': 'object'}

Link: https://lore.kernel.org/r/20230124-b4-amlogic-bindings-fixups-v1-9-44351528957e@linaro.org


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>