samples: move mic/mpssd example code from Documentation

Move mic/mpssd examples to samples and remove it from Documentation
Makefile. Create a new Makefile to build mic/mpssd. It can be built
from top level directory or from mic/mpssd directory:

Run make -C samples/mic/mpssd or cd samples/mic/mpssd; make

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>