serial: msm_serial_hs: Add snapshot of serial highspeed driver

This change adds a snapshot of the BLSP based HSUART driver
from kernel-4.14 baseline.
This is snapshot of the BLSP based HSUART driver as of
msm-4.14 'commit 78bed541 ("Merge "msm:
camera: hyp: To fix Stack overflow"")'.

Change-Id: I39b47c672d8f38a55989d747fbd6ebdcbe9af68b
Signed-off-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>
Signed-off-by: Chetan C R <cchinnad@codeaurora.org>