ASoC: SOF: add a flag to indicate the system suspend target

Add flag 's0_suspend' to indicate if the system is entering S0ix or
not.
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/20191025224122.7718-20-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/sof-priv.h

@@ -398,6 +398,8 @@ struct snd_sof_dev {
 
 	/* power states related */
 	enum sof_d0_substate d0_substate;
+	/* flag to track if the intended power target of suspend is S0ix */
+	bool s0_suspend;
 
 	/* DSP firmware boot */
 	wait_queue_head_t boot_wait;