msm: mhi_dev: Add MHI device driver snapshot

Modem host interface (MHI) device driver is
used to communicate between host and device
over PCIe.

This snapshot is taken as of msm-4.4
'commit <4f1f60e00d6a> ("Merge "ARM: dts:
msm: add nt35597 sharp panel node for sdm660"")'.

Change-Id: I7a396218003b7efadbdccf158ecf036dfb5ce845
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>