ASoC: msm: qdp6v2: Add copy interface to transfer data to AFE proxy

In USB peripheral mode, USB gadget doesn't get notification when pc stops
sending data, but hr timer is still running periodically, this leads to
repeated data sent to far end during voice call.Though USB is not sending
data, hr timer runs periodically and makes pointer misalignment.
As the buffers are huge (98K in playback path, and 98K in capture path),
causes latency issues in voice call, in hr timer based data transfer
to AFE. To solve these issues, implement copy interface to avoid timer
based data transfer, for MDM voice over USB usecase. Playback and capture
copy functions are added to transfer data between usb gadget and dsp.

Change-Id: I66bbcc9eb2f319bd326814f6e12cf6276ed08131
Signed-off-by: Viraja Kommaraju <virajak@codeaurora.org>