tools: bootconfig: Add bootconfig test script

Add a bootconfig test script to ensure the tool and
boot config parser are working correctly.

Link: http://lkml.kernel.org/r/157867224728.17873.18114241801246589416.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>