arm64: dts: meson-g12a: Fix internal Ethernet PHY unit name

Documentation/devicetree/bindings/net/ethernet-phy.yaml defines that the
node name for Ethernet PHYs should match the following pattern:
  ^ethernet-phy(@[a-f0-9]+)?$

Replace the underscore with a hyphen to adhere to this binding.

Fixes: 280c17df8f ("arm64: dts: meson: g12a: add mdio multiplexer")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230111211350.1461860-6-martin.blumenstingl@googlemail.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi

@@ -1694,7 +1694,7 @@
 					#address-cells = <1>;
 					#size-cells = <0>;
 
-					internal_ephy: ethernet_phy@8 {
+					internal_ephy: ethernet-phy@8 {
 						compatible = "ethernet-phy-id0180.3301",
 							     "ethernet-phy-ieee802.3-c22";
 						interrupts = <GIC_SPI 9 IRQ_TYPE_LEVEL_HIGH>;