drivers/rtc: remove unneeded ifdef CONFIG_PM

Because CONFIG_PM is a precondition to CONFIG_ACPI, the ifdef CONFIG_PM
within ifdef CONFIG_ACPI is redundant.

Signed-off-by: Christian Dietrich <qy03fugy@stud.informatik.uni-erlangen.de>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>