ASoC: SOF: Do nothing when DSP PM callbacks are not set

This provides a better separation between runtime and PM sleep
callbacks.

Only do nothing if given runtime flag is set and calback is not set.

With the current implementation, if PM sleep callback is set but runtime
callback is not set then at runtime resume we reload the firmware even
if we do not support runtime resume callback.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@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/20200515135958.17511-2-kai.vehmanen@linux.intel.com


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