UCM2: Intel: sof-hda-dsp: Fix handling of empty sys_vendor string

[GitHub pull_request - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-ucm-conf pull request #463 was opened from singalsu:

The mistake in UCM syntax caused in alsaucm start error:

ALSA lib ucm_cond.c:367:(if_eval) unknown If.Condition.Type

Fixes: 13022a97711d ("sof-hda-dsp: Fix the case where sysfs dmi
       sys_vendor attribute is not set")

Request URL   : https://github.com/alsa-project/alsa-ucm-conf/pull/463
Patch URL     : https://github.com/alsa-project/alsa-ucm-conf/pull/463.patch
Repository URL: https://github.com/alsa-project/alsa-ucm-conf