ASoC: pxa: Convert corgi to use snd_soc_register_card()

Use snd_soc_register_card() instead of creating a "soc-audio" platform device.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>