ASoC: Use core pm_runtime callbacks for omap-mcpdm

Now that the core holds a pm_runtime reference to the device while the
link is active there is no need for the driver to do so.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

diff --cc sound/soc/omap/omap-mcpdm.c
Simple merge