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>

include/linux/clocksource.h

@@ -319,13 +319,6 @@ static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz)
 	__clocksource_updatefreq_scale(cs, 1000, khz);
 }
 
-static inline void
-clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
-{
-	return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
-				      NSEC_PER_SEC, minsec);
-}
-
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 extern void
 update_vsyscall(struct timespec *ts, struct timespec *wtm,