ASoC: SOF: Add userspace ABI support

Add userspace ABI for audio userspace application IO outside of regular
ALSA PCM and kcontrols. This is intended to be used to format
coefficients and data for custom processing components.

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>