selftests/ftrace: Add a test to probe module functions

selftests/ftrace: Add a test to probe module functions

Add a kprobes test to ensure that we are able to add a probe on a
module function using 'p <mod>:<func>' format, with/without having to
specify a probe name.

Link: http://lkml.kernel.org/r/2d8087e25a7ad9206f3e2b7b4bb0c3c86eaa38af.1499453040.git.naveen.n.rao@linux.vnet.ibm.com
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>