dt-bindings: i2c: omap: Add new compatible for J721E SoCs

J721E SoCs have same I2C IP as OMAP SoCs. Add new compatible to
handle J721E SoCs.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>