ARM: S5PV310: Limit the irqs which support cascade interrupt

The irqs from SPI(0) to SPI(39) and SPI(51), SPI(53) are connected to the
interrupt combiner. This patch limits the irqs which should be initialized
to support cascade interrupt.

Signed-off-by: Changhwan Youn <chaos.youn@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>