dt-bindings: i2c: Add compatible string for AM64 SoC

Add compatible string for AM64 SoC in device tree binding of OMAP I2C
modules as the same IP is used.
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

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

@@ -8,6 +8,7 @@ Required properties :
 	"ti,omap4-i2c" for OMAP4+ SoCs
 	"ti,am654-i2c", "ti,omap4-i2c" for AM654 SoCs
 	"ti,j721e-i2c", "ti,omap4-i2c" for J721E SoCs
+	"ti,am64-i2c", "ti,omap4-i2c" for AM64 SoCs
 - ti,hwmods : Must be "i2c<n>", n being the instance number (1-based)
 - #address-cells = <1>;
 - #size-cells = <0>;