ARM: S3C64XX: Dynamically assign interrupts for CPU PMIC on Cragganmore

Now that the WM831x driver uses irq_domain we can happily allow it to
assign its own IRQs.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>