topology: decode: Remove decoding values for enum control

topology: decode: Remove decoding values for enum control

Values have no representation in standard ALSA configuration files,
therefore there is no need to populate them. Also memory for values
wasn't allocated which was causing undefined behaviour.

Signed-off-by: Piotr Maziarz <piotrx.maziarz@linux.intel.com>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Reviewed-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>