ARM: dts: BCM5301X: Add Ethernet interfaces links

Northstar SoCs have 3 usable Ethernet interfaces each connected to one
of switch ports. They all use fixed links.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20230707091519.21673-1-zajec5@gmail.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>

Author: Rafał Miłecki

arch/arm/boot/dts/broadcom/bcm-ns.dtsi

@@ -272,14 +272,32 @@
 
 		gmac0: ethernet@24000 {
 			reg = <0x24000 0x800>;
+			phy-mode = "internal";
+
+			fixed-link {
+				speed = <1000>;
+				full-duplex;
+			};
 		};
 
 		gmac1: ethernet@25000 {
 			reg = <0x25000 0x800>;
+			phy-mode = "internal";
+
+			fixed-link {
+				speed = <1000>;
+				full-duplex;
+			};
 		};
 
 		gmac2: ethernet@26000 {
 			reg = <0x26000 0x800>;
+			phy-mode = "internal";
+
+			fixed-link {
+				speed = <1000>;
+				full-duplex;
+			};
 		};
 
 		gmac3: ethernet@27000 {