update sample script ftrace.kp

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@gmail.com>
support multi eventdef

Usage:
trace 'EVENTDEF1; EVENTDEF2' function (e) { BODY }

trace 'EVENTDEF1 /filter1/; EVENTDEF2 /filter2/' function (e) { BODY }

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@gmail.com>