MIPS: xilfpga: Add DT node for AXI I2C

The xilfpga platform has an AXI I2C Bus master with a temperature
sensor connected to it.

Add the device tree node to use them.
Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14594/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/boot/dts/xilfpga/nexys4ddr.dts

@@ -54,6 +54,28 @@ axi_uart16550: serial@10400000 {
 		interrupt-parent = <&axi_intc>;
 		interrupts = <0>;
 	};
+
+	axi_i2c: i2c@10A00000 {
+	    compatible = "xlnx,xps-iic-2.00.a";
+	    interrupt-parent = <&axi_intc>;
+	    interrupts = <4>;
+	    reg = < 0x10A00000 0x10000 >;
+	    clocks = <&ext>;
+	    xlnx,clk-freq = <0x5f5e100>;
+	    xlnx,family = "Artix7";
+	    xlnx,gpo-width = <0x1>;
+	    xlnx,iic-freq = <0x186a0>;
+	    xlnx,scl-inertial-delay = <0x0>;
+	    xlnx,sda-inertial-delay = <0x0>;
+	    xlnx,ten-bit-adr = <0x0>;
+	    #address-cells = <1>;
+	    #size-cells = <0>;
+
+	    ad7420@4B {
+		compatible = "adi,adt7420";
+		reg = <0x4B>;
+	    };
+	} ;
 };
 
 &ext {