ASoC: SOF: Intel: hda: Introduce skip_imr_boot flag

Use a dedicated flag instead of directly checking the
sdev->system_suspend_target to decide if we need to skip IMR boot due to
too deep sleep state where the memory used for IMR booting will not retain
its content.

The skip_imr_boot flag will be set true during suspend if the target state
is deeper than S3 and reset back to false on successful boot to re-enable
IMR booting in shallower sleep states.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220712120936.28072-2-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>