Update the aoa-soundbus framework to use dev_pm_ops rather than the
deprecated legacy suspend and resume callbacks.

Since there isn't anything special to do at the bus level the bus driver
does not have to implement any callbacks. The device driver core will
automatically pick up and execute the device's PM ops.

As there is only a single aoa-soundbus driver implementing suspend and
resume, update both the core and driver at the same time to avoid
unnecessary code churn.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>