drivers char: add okl4_pipe driver

A simple driver for directing using OKL4 hypervisor pipe IPC
objects.

Change-Id: I0330fdd3d73dfeca2d5626e521b64dd6639cfdf6
Signed-off-by: Carl van Schaik <carl@cog.systems>
Git-commit: 55a9a3cd481049d3f60caef871d14d13c507dcb9
Git-repo: https://github.com/CogSystems/linux-msm.git


Signed-off-by: Minming Qi <mqi@codeaurora.org>