ASoC: Remove unused hw_write_t type

ASoC: Remove unused hw_write_t type

Commit 81da8a0b7975 ("ASoC: remove codec hw_write/control_data") removed
use of hw_write_t in struct snd_soc_codec, but it left type definition.
Fully clean it up.

Fixes: 81da8a0b7975 ("ASoC: remove codec hw_write/control_data")
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20220610124420.4160986-1-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>