i2c: emev2: add driver

Add a basic driver for the Renesas EMEV2 SoC. Based on the driver from
the BSP which was first worked on by Ian, and made ready for upstream by
me.

Signed-off-by: Ian Molton <ian.molton@codethink.co.uk>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-emev2.txt

@@ -0,0 +1,22 @@
+Device tree configuration for Renesas EMEV2 IIC controller
+
+Required properties:
+- compatible      : "renesas,iic-emev2"
+- reg             : address start and address range size of device
+- interrupts      : specifier for the IIC controller interrupt
+- clocks          : phandle to the IP core SCLK
+- clock-names     : must be "sclk"
+- #address-cells  : should be <1>
+- #size-cells     : should be <0>
+
+Example:
+
+	iic0: i2c@e0070000 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "renesas,iic-emev2";
+		reg = <0xe0070000 0x28>;
+		interrupts = <0 32 IRQ_TYPE_EDGE_RISING>;
+		clocks = <&iic0_sclk>;
+		clock-names = "sclk";
+	};