ARM: dts: renesas: Add compatible properties to KSZ8081 Ethernet PHYs

Add compatible values to Ethernet PHY subnodes representing Micrel
KSZ8081 PHYs on RZ/G1 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>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/ec5c7dadf3c0fe5e47dfbae72fb435047203ad06.1631174218.git.geert+renesas@glider.be

arch/arm/boot/dts/r8a7742-iwg21d-q7-dbcm-ca.dts

@@ -66,6 +66,8 @@ &ether {
 	status = "okay";
 
 	phy1: ethernet-phy@1 {
+		compatible = "ethernet-phy-id0022.1560",
+			     "ethernet-phy-ieee802.3-c22";
 		reg = <1>;
 		micrel,led-mode = <1>;
 	};