selftests: ftrace: Add a testcase for probepoint

Add a testcase for probe point definition. This tests
symbol, address and symbol+offset syntax. The offset
must be positive and smaller than UINT_MAX.

Link: http://lkml.kernel.org/r/152129043097.31874.14273580606301767394.stgit@devbox

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