vservices: serial: Add the serial protocol and drivers

Adds the virtual services serial protocol and tty drivers
for virtual serial and console.

Change-Id: I2dd86a677406d6b74b0e02e5fda720eaf9edcd62
Signed-off-by: Carl van Schaik <carl@cog.systems>
Git-commit: 29f5766e09adb6064b01bf20e76c117bcfa94e41
Git-repo: https://github.com/CogSystems/linux-msm/commits/msm-4.9-hyp


Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>