APR: Add G-link transport layer for packet routing

APR driver was using SMD as the underlying transport layer. In order
to provide a unified IPC solution, G-link is introduced as the replacement
which APR adapts as the new transport layer for audio packet routing.

Change-Id: I60d96e39ce665b808498d1130e371df8288e370a
Signed-off-by: Helen Zeng <xiaoyunz@codeaurora.org>
Signed-off-by: Deven Patel <cdevenp@codeaurora.org>