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

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

Migrate from using glink api to rpmsg api:
- removed not used glink functionality
- removed not used kernel api to spcom functionality
- implemented rpmsg driver registration for each new spcom channel
open/close/tx/rx/poll flows fixes:
- rpmsg_abort flag introduced to synchronize close() of a channel with
  pending sending or receiving data from the channel
- tx implemented as rpmsg_trysend() every 10ms (timeout_msec total)
- poll imlemented link up/down events as first/last rpmsg device
  probed/removed
- locking

ION api replaced by dma-buf:
ION api depricated.
This change implements following functionality:
Lock/unlock shared buffer by reference counting on underline dma-buf.
Translation user allocated shared buffer virtual address to
physical address (to enable SPU access to the buffer).

Change-Id: I28d704b18a3b0de9711ff3235c3f5551e7302557
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>