drivers/rtc/rtc-s5m.c: s5m_rtc_{suspend,resume}() should depend on CONFIG_PM_SLEEP

If CONFIG_PM_SLEEP=n:

drivers/rtc/rtc-s5m.c:643: warning: `s5m_rtc_resume' defined but not used
drivers/rtc/rtc-s5m.c:654: warning: `s5m_rtc_suspend' defined but not used

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>