ARM: dts: Enable Ethernet on STi's B2199 board

The B2199 board is mounted with Realtek RTL8367 switch.
We consider the bootloader will have intiliazed the switch before jumping into
the kernel, so we declare it as a fixed link.
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>

arch/arm/boot/dts/stih418-b2199.dts

@@ -24,6 +24,7 @@ memory {
 
 	aliases {
 		ttyAS0 = &sbc_serial0;
+		ethernet0 = &ethernet0;
 	};
 
 	soc {
@@ -101,5 +102,12 @@ phy_port1: port@9b2a000 {
 		st_dwc3: dwc3@8f94000 {
 			status = "okay";
 		};
+
+		ethernet0: dwmac@9630000 {
+			st,tx-retime-src = "clkgen";
+			status = "okay";
+			phy-mode = "rgmii";
+			fixed-link = <0 1 1000 0 0>;
+		};
 	};
 };