ASoC: SOF: pm: Fix prepare callback behavior for OF usecase

ASoC: SOF: pm: Fix prepare callback behavior for OF usecase

On i.MX platforms PM is not managed via ACPI although CONFIG_ACPI
can be set. So, in order to correctly set the system target state
we introduce a flag for platforms that require to use acpi target
states.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20200921105038.2909899-1-kai.vehmanen@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>