msm: Add driver to communicate with voice services on DSP over APR

Add new driver in kernel to expose voice services on DSP over APR.
Userspace client voice modules in user space will use read/write
interface to send/receive messages between voice services on DSP
and APSS via APR.

CRs-fixed: 642690
Change-Id: Icc75b01e19b757d7da81f143fc10f09185e92d31
Signed-off-by: Vicky Sehrawat <vickys@codeaurora.org>