Instead of using clocksource_register() we use
clocksource_register_hz() as suggested

From kernel patch c7f798e3722610d486e951f04bbc00b6ba124d62
    clocksource: Get rid of clocksource_calc_mult_shift()

    No one is using this, so encourage the use of
    clocksource_register_hz/khz(), and drop this helper.

    Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
    [jstultz: tweaked commit message]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Federico Vaga <federico.vaga@cern.ch>