ARM: S3C24XX: remove unused spi gpio setup functions

A grep through the kernel source revealed that neither the
config-options nor the defined functions are used anywhere
in the kernel.

There was also no activity in this regard through the last kernel
releases, so it seems this situation will not change in the future.

Therefore this patch removes this seemingly dead code.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>