ARM: S5P64X0: Add GPIOlib support for S5P6450

Already can support S5P6440 GPIOlib but S5P6450. This patch changes regarding
S5P6440 GPIO definitions so that can be used it from S5P6450 and adds S5P6450
GPIO chips.

Tested-by: Atul Dahiya <atul.dahiya@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>