ARM: S5P: Add function to register gpio interrupt bank data

This patch removes all global data from common s5p gpio interrupt
handler code. This enables to reuse this code on EXYNOS4 platform.
Instead of global data (IRQ_GPIOINT interrupt number,
S5P_GPIOINT_GROUP_MAXNR groups count), a s5p_register_gpioint_bank()
function is introduced. It is aimed to be called from gpiolib init.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>