ASoC: SOF: add helper to check if we should enter d0i3 suspend

Add helper to check if the DSP should be put in D0i3. This function
returns true if a stream has ignored the SUSPEND trigger to keep the
pipelines running in the DSP.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191111223343.19986-4-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>