ASoC: compress: Fix memory leak from snd_soc_new_compress

Change kzalloc to devm_kzalloc, so compr gets automatically freed when
it's no longer needed.

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