[ARM] S3C24XX: Split PM code from arch/arm/plat-s3c24xx/irq.c

Split the PM code out of arch/arm/plat-s3c24xx/irq.c to
remove some of the #ifdefs being used. Also fix a couple
of places where the absecnce of a function was redefined
to the same thing.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>