ASoC: Samsung: Debug PCM platform device name

The PCM controller platform devices are registered by the
name 'samsung-pcm', so use the same in the CPU driver.

Signed-off-by: Jassi Brar <jassi.brar@samsung.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>