soc: qcom: add secure processor communication (spcom) driver

This driver supports communication with secure processor subsystem
over glink transport layer.
The communication is based on using shared memory and interrupts.
This driver exposes interface to both kernel and user space.

Change-Id: I21ad3bac5d1b0cc7a4da616040c81f117c655435
Signed-off-by: Kineret Berger <kberger@codeaurora.org>