ASoC: SOF: inform DSP that driver is going to be removed

This patch invokes the DSP power down notifier to inform
DSP that driver is going to be removed.
The module removal entails DSP power down, disabling of
IRQs and more. Therefore it is highly recommended to inform
the DSP about this upcoming event.

Due to hardware limitations on some Intel platforms it is necessary
to power gate all LPSRAM banks that were enabled prior to controller
reset. Otherwise, an attempt to write LPSRAM control registers may
have no effect.

Signed-off-by: Marcin Rajwa <marcin.rajwa@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20200515135958.17511-4-kai.vehmanen@linux.intel.com


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