msm8660: scm-io: Support secure io operations

Some registers accesses need to be done securely. Implement a thin
API similar to readl/writel which requests the secure side to
read or write a register securely.

Change-Id: If41f7321877ceead7ab38f36faeee1114bd82f4d
Signed-off-by: Ajay Dudani <adudani@codeaurora.org>
5 files changed