[ARM] S3C24XX: Fix bug in IRQ_EINT_BIT() calculation

There's a bug in calculation of IRQ_EINT_BIT introduced on the test
branch for pm changes for s3c by Ben Dooks fixed in this patch.

There's also a bit of a mystery about how wake gets to wake EINT
set of interrupts, I added a couple of lines that make it work for
EINT4+ but not sure what's meant to be there for EINT0-3.

Still, this gets GTA02 resume working again.

Signed-off-by: Andy Green <andy@openmoko.com>
[ben-linux@fluff.org: remove irq-pm.c change]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>