dt-bindings: i2c: omap: Add new compatible for AM654 SoCs

AM654 SoCs have same I2C IP as OMAP SoCs. Add new compatible to
handle AM654 SoCs. While at that reformat the existing compatible list
for older SoCs to list one valid compatible per line.
Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

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

 I2C for OMAP platforms
 
 Required properties :
-- compatible : Must be "ti,omap2420-i2c", "ti,omap2430-i2c", "ti,omap3-i2c"
-  or "ti,omap4-i2c"
+- compatible : Must be
+	"ti,omap2420-i2c" for OMAP2420 SoCs
+	"ti,omap2430-i2c" for OMAP2430 SoCs
+	"ti,omap3-i2c" for OMAP3 SoCs
+	"ti,omap4-i2c" for OMAP4+ SoCs
+	"ti,am654-i2c", "ti,omap4-i2c" for AM654 SoCs
 - ti,hwmods : Must be "i2c<n>", n being the instance number (1-based)
 - #address-cells = <1>;
 - #size-cells = <0>;