ASoC: fsl: use snd_soc_register_card to register the card

Use snd_soc_register_card() instead of platform_device_alloc("soc-audio")
to register the sound card from the machine drivers.  The use of
platform_device_alloc is deprecated.

Although several other drivers still use platform_device_alloc(), the
Freescale drivers were not using it to pass driver data.  Instead of fixing
the driver data usage, it's better to replace the deprecated code.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>