irqchip: exynos-combiner: Correct combined IRQs for exynos4

This patch corrects combined IRQs for exynos4 series platform. The exynos4412
has four extra combined irq group and the exynos4212 has two more combined
irqs
than exynos4210. Each irq is mapped to IRQ_SPI(xx). Unfortunately, extra 4
combined IRQs isn't sequential. So, we need to map the irqs manually.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[kgene.kim@samsung.com: changes moved into drivers/irqchip/]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>