ASoC: hdac_hdmi: use devm_kzalloc for all structures

Loading/unloading modules exposes issues with memory allocation, which
is a mix of devm_kzalloc and manual kzalloc. Move to devm_k routines
everywhere to simplify all this.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>