arm: dts: am437x: sync cpsw/mdio/phy with latest linux - drop phy_id

Synchronize CPSW/MDIO/PHY DT nodes with latest linux - replace deprecated
phy_id property with phy-handle.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Lokesh Vutla <lokeshvutla@ti.com>
diff --git a/arch/arm/dts/am437x-idk-evm.dts b/arch/arm/dts/am437x-idk-evm.dts
index 19d1462..8f6824c 100644
--- a/arch/arm/dts/am437x-idk-evm.dts
+++ b/arch/arm/dts/am437x-idk-evm.dts
@@ -385,6 +385,7 @@
 };
 
 &mac {
+	slaves = <1>;
 	pinctrl-names = "default", "sleep";
 	pinctrl-0 = <&cpsw_default>;
 	pinctrl-1 = <&cpsw_sleep>;
@@ -396,10 +397,14 @@
 	pinctrl-0 = <&davinci_mdio_default>;
 	pinctrl-1 = <&davinci_mdio_sleep>;
 	status = "okay";
+
+	ethphy0: ethernet-phy@0 {
+		reg = <0>;
+	};
 };
 
 &cpsw_emac0 {
-	phy_id = <&davinci_mdio>, <0>;
+	phy-handle = <&ethphy0>;
 	phy-mode = "rgmii";
 };