ASoC: SOF: add a flag suspend_ignored for sof stream

ASoC: SOF: add a flag suspend_ignored for sof stream

Add a suspend_ignored flag to snd_sof_pcm_stream that will be used to
decide if the corresponding FW pipeline should be kept active to perform
always on tasks when the system is entering the S0ix state.

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/20191025224122.7718-21-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>