ASoC: Fix DaVinci module unload error

Fix for the error when the audio module is unloaded.  On unregistering
the platform_device, platform_device_release will free the platform
data.If platform data is static the kernel panics when it is freed.
Instead use the platform device helper function to add data.

This change has been tested on DM644x EVM, DM644x SFFSDR and DM355 EVM.

Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>