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

This driver supports communication with secure processor subsystem
(SPSS) over rpmsg and ungerlying glink transport layer. The
communication is based on using shared memory and interrupts.
Add snapshot for spcom driver from msm-4.19 commit b3159f82fb1b
("soc: qcom: spcom: fix active pid clean up").

Change-Id: Ic35584e8770980e2f480949808529a1d933da1f6
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>