ARM: GIC: move gic_chip_data structure declaration to header

Since Samsung EXYNOS4210 cannot support register banking in GIC,
so needs to update CPU interface base address.
The 'gic_chip_data' is used for it, this patch moves gic_chip_data
structure declaraton to arch/arm/include/asm/hardware/gic.h to use
it.

Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Changhwan Youn <chaos.youn@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>