arm64: dts: renesas: Add compatible properties to RTL8211E Ethernet PHYs

Add compatible values to Ethernet PHY subnodes representing Realtek
RTL8211E PHYs on RZ/G2 boards.  This allows software to identify the PHY
model at any time, regardless of the state of the PHY reset line.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/3b366e3dddd4d3cd7e89b92d3a8f78f6dc18e244.1631174218.git.geert+renesas@glider.be

arch/arm64/boot/dts/renesas/cat875.dtsi

@@ -21,6 +21,8 @@ &avb {
 	status = "okay";
 
 	phy0: ethernet-phy@0 {
+		compatible = "ethernet-phy-id001c.c915",
+			     "ethernet-phy-ieee802.3-c22";
 		reg = <0>;
 		interrupt-parent = <&gpio2>;
 		interrupts = <21 IRQ_TYPE_LEVEL_LOW>;

arch/arm64/boot/dts/renesas/hihope-rzg2-ex.dtsi

@@ -24,6 +24,8 @@ &avb {
 	status = "okay";
 
 	phy0: ethernet-phy@0 {
+		compatible = "ethernet-phy-id001c.c915",
+			     "ethernet-phy-ieee802.3-c22";
 		reg = <0>;
 		interrupt-parent = <&gpio2>;
 		interrupts = <11 IRQ_TYPE_LEVEL_LOW>;