ARM: S5P64X0: Fix GPIO rbank support

The patch removes s3c_gpio_lock/unlock to avoid acquiring the lock
recursively as lock is already acquired by calling function.

Signed-off-by: Atul Dahiya <atul.dahiya@samsung.com>
Signed-off-by: Sangbeom Kim <sbkim73@samsung.com>
[kgene.kim@samsung.com: removed useless variable due to this]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>