Comment # 8 on bug 1189688 from Takashi Iwai

Kernel has a few different drivers for the Intel chip, one is the standard
(legacy) HD-audio driver, and another is ASoC Intel SST driver.  There is a
newcomer, ASoC SOF Intel HD-audio driver, too.

The last two support the built-in mic (d-mic) that is driven over another bus
than HD-audio bus, and they need own firmware files.

The firmware file, skl_hda_dsp_generic-tplg.bin, could be compiled from the
standard file included in alsa-topology-conf package.

Could you try the following?

% sudo zypper in alsa-topology-conf
% alsatplg -c /usr/share/alsa/topology/hda-dsp/skl_hda_dsp_generic-tplg.conf -o
skl_hda_dsp_generic-tplg.bin
% sudo cp skl_hda_dsp_generic-tplg.bin /lib/firmware

Then reboot and retest.