tools: move laptops dslm tool from Documentation

Move laptops dslm tool to tools/laptop/dslm and remove it from
Documentation Makefile. Update location information for this
tool. Create a new Makefile to build dslm. It can be built
from top level directory or from laptops directory:

Run make -C tools/laptop/dslm or cd tools/laptop/dslm; make

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