ARM: dts: stm32: Add ethernet dwmac on stm32mp1

Add Ethernet support (Synopsys MAC IP 4.20a) on stm32mp1 SOC.
Enable feature supported by the stmmac driver, such as TSO.
Signed-off-by: Christophe Roullier <christophe.roullier@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp157c.dtsi

@@ -978,6 +978,36 @@ crc1: crc@58009000 {
 			status = "disabled";
 		};
 
+		stmmac_axi_config_0: stmmac-axi-config {
+			snps,wr_osr_lmt = <0x7>;
+			snps,rd_osr_lmt = <0x7>;
+			snps,blen = <0 0 0 0 16 8 4>;
+		};
+
+		ethernet0: ethernet@5800a000 {
+			compatible = "st,stm32mp1-dwmac", "snps,dwmac-4.20a";
+			reg = <0x5800a000 0x2000>;
+			reg-names = "stmmaceth";
+			interrupts-extended = <&intc GIC_SPI 61 IRQ_TYPE_LEVEL_HIGH>;
+			interrupt-names = "macirq";
+			clock-names = "stmmaceth",
+				      "mac-clk-tx",
+				      "mac-clk-rx",
+				      "ethstp",
+				      "syscfg-clk";
+			clocks = <&rcc ETHMAC>,
+				 <&rcc ETHTX>,
+				 <&rcc ETHRX>,
+				 <&rcc ETHSTP>,
+				 <&rcc SYSCFG>;
+			st,syscon = <&syscfg 0x4>;
+			snps,mixed-burst;
+			snps,pbl = <2>;
+			snps,axi-config = <&stmmac_axi_config_0>;
+			snps,tso;
+			status = "disabled";
+		};
+
 		usbh_ohci: usbh-ohci@5800c000 {
 			compatible = "generic-ohci";
 			reg = <0x5800c000 0x1000>;