soc: qcom: msm_smd: Add snapshot of Shared memory driver

This is a snapshot of the SMD driver as of msm-4.4 commit
<bb3bb010ec74> (Merge "ASoC: wcd9xxx: restrict debugfs permission")

Shared memory data[SMD] drivers provides data communication to
remote peripherals such as Modem and ADSP over shared memory.

CRs-Fixed: 2144497
Change-Id: I50ded677a10dae3910b8369e6c17f175dda3edf5
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>