selftests/ftrace: Add a testcase for kprobe event naming

Add a testcase for kprobe event naming. This testcase checks whether the
kprobe events can automatically ganerate its event name on normal
function and dot-suffixed function.  Also it checks whether the kprobe
events can correctly define new event with given event name and group
name.

Link: http://lkml.kernel.org/r/61ae96fd1fcd14ee652c8b6525c218b8661bb0d2.1499453040.git.naveen.n.rao@linux.vnet.ibm.com



Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[Updated tests to use vfs_read and symbols with '.isra.',
added check for kprobe_events and a command to clear it on exit,
various additional checks and tests]
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>