change the method for register dai and pcm
  - let the atmel-ssc-dai no longer as a standalone platform device
  - remap ssc and then register dai directly
  - register pcm from dai directly
  - modify the code which related with this change
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>