ARM: S3C24XX: Fix gpiolib support for ports K..M

S3C2443 and S3C2416 has 12 GPIO banks (from A to M), increase
ARCH_NR_GPIOS for this architectures.

Also typo from previous commit has been fixed: CONFIG_CPU_S3C24XX
instead CONFIG_CPU_244X.

Signed-off-by: Yauhen Kharuzhy <jekhor@gmail.com>
Tested-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>