dt-bindings: sound: intel, keembay-i2s: Add new compatible string

Add a new compatible string that configures the interface to the
desired format.

Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
Reviewed-by: Sia Jee Heng <jee.heng.sia@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200811041836.999-3-michael.wei.hong.sit@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>