drivers/rtc/rtc-sa1100.c: move clock enable/disable to probe/remove

The original sa1100_rtc_open/sa1100_rtc_release will be called when the
/dev/rtc0 is opened or closed.  In fact, these two functions will
enable/disable the clock.  Disabling clock will make rtc not work.  So
only enable/disable clock when probe/remove the device.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: Leo Song <liangs@marvell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>