ASoC: mfld-compress: implement .power callback

.power callback is required to invoked for compressed audio as well to turn
on/off sst, so invoke them

Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>