ARM: shmobile: alt: add I2C1 DT support

Defines the board-dependent part of the I2C1 device.
Signed-off-by: NUlrich Hecht <ulrich.hecht+renesas@gmail.com>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a7794-alt.dts

@@ -115,6 +115,11 @@
 		renesas,groups = "eth_link_b", "eth_mdio_b", "eth_rmii_b";
 		renesas,function = "eth";
 	};
+
+	i2c1_pins: i2c1 {
+		renesas,groups = "i2c1";
+		renesas,function = "i2c1";
+	};
 };
 
 &cmt0 {
@@ -134,6 +139,14 @@
 	};
 };
 
+&i2c1 {
+	pinctrl-0 = <&i2c1_pins>;
+	pinctrl-names = "default";
+
+	status = "okay";
+	clock-frequency = <400000>;
+};
+
 &scif2 {
 	status = "okay";
 };