Don't rely on internal Skylake-specific data structures, use
generic interface to let other drivers use the same machine driver
as is, e.g. SOF to support HDaudio codecs and HDMI outputs.

Tested on LeafHill CRB board, no regression seen with this change.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>