ASoC: Intel: skl_hda_dsp_generic: add DMIC support

Add dmic dai links using naming conventions used in
previous machine drivers.

Tested on whiskylake & icelake with SOF driver. Due
to a missing topology file, the DMIC functionality
could not be tested with the Skylake driver but was
tested for non-regressions on a GeminiLake platform
without DMICs.

Signed-off-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>