ARM: dts: uniphier: add pinmux node for I2C ch4

This will be needed for UniPhier PH1-LD11 and PH1-LD20 SoCs.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/boot/dts/uniphier-pinctrl.dtsi

@@ -63,6 +63,11 @@ pinctrl_i2c3: i2c3_grp {
 		function = "i2c3";
 	};
 
+	pinctrl_i2c4: i2c4_grp {
+		groups = "i2c4";
+		function = "i2c4";
+	};
+
 	pinctrl_uart0: uart0_grp {
 		groups = "uart0";
 		function = "uart0";