ASoC: tas2781: Add Header file for tas2781 driver

Create Header file for  tas2781 driver.

Signed-off-by: Shenghao Ding <13916275206@139.com>
Link: https://lore.kernel.org/r/20230618122819.23143-1-13916275206@139.com


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