topology: decoder: fix wrong sizeof for enum control allocation in dapm

topology: decoder: fix wrong sizeof for enum control allocation in dapm

The tplg_calloc() call for enum control in the dapm widget kcontrol
decode loop used sizeof(*mt) (mixer template) instead of sizeof(*et)
(enum template). On 64-bit systems, snd_tplg_mixer_template is 72 bytes
while snd_tplg_enum_template is 80 bytes, causing an 8-byte heap buffer
overflow when the enum fields (texts, values pointers) were written past
the allocated block. This resulted in heap corruption and e.g. glibc
malloc hit an assert.

Closes: https://github.com/alsa-project/alsa-lib/pull/501
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>