dt-bindings: tas2770: Mark ti,asi-format to deprecated

Mark the property ti,asi-format to deprecated as it is no longer
supported.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Link: https://lore.kernel.org/r/20200924142641.12355-1-dmurphy@ti.com


Signed-off-by: Mark Brown <broonie@kernel.org>