ARM: S3C24XX: Fix nand partition table for s3c24XX

This patch fixes the partition table as existing partition table have last
partition size fixed and can't utilize available memory proprly if size is
more than 64M.

Signed-off-by: Atul Dahiya <atul.dahiya@samsung.com>
Signed-off-by: Sangbeom Kim <sbkim73@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>