selftests/ftrace: Add testcases for dynamic event

Add common testcases for dynamic_events interface.
 - Add/remove kprobe events via dynamic_events
 - Add/remove synthetic events via dynamic_events
 - Selective clear events (clear events other interfaces)
 - Genelic clear events ("!LINE" syntax)

Link: http://lkml.kernel.org/r/154140872590.17322.10394440849261743052.stgit@devbox

Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>