drivers/rtc/rtc-s3c.c: delete duplicate clock control

The current functions in s3c-rtc driver execute clk_enable/disable() to
control clocks and some functions execute s3c_rtc_alarm_clk_enable()
unnecessarily.  So this patch deletes the duplicate clock control and
spilts s3c_rtc_alarm_clk_enable() out as
s3c_rtc_enable_clk()/s3c_rtc_disable_clk() to improve readability.
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Kukjin Kim <kgene@kernel.org>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>