selftests: tracing: Add tprobe enable/disable testcase

Commit 2867495dea86 ("tracing: tprobe-events: Register tracepoint when
enable tprobe event") caused regression bug and tprobe did not work.
To prevent similar problems, add a testcase which enables/disables a
tprobe and check the results.

Link: https://lore.kernel.org/r/176252610176.214996.3978515319000806265.stgit@devnote2
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>