drivers: soc: add snapshot of scm driver

This is a snapshot of scm driver as of msm-4.14 commit <55e5efd553c10ef>
(Merge "nl80211: Fix external_auth check for offloaded authentication").

Change-Id: I17c0b940daef17647a779ae079914cd795503074
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>