ENGR00161014 ASoC: don't clobber platform DMA driver ops

ENGR00161014 ASoC: don't clobber platform DMA driver ops

Previously, only one static struct for ops existed for all
platform DMA drivers to share.  Half of the ops are shared
functions which don't have stubs in the ALSA core.  The
other half are initialized to point directly to ops in the
platform driver.  This creates problems where each time
soc_new_pcm is called, the new platform driver's ops would
overwrite a subset of the ops.

Signed-off-by: Alan Tull <alan.tull@freescale.com>