ARM: EXYNOS: To use common config for EXYNOS4 and EXYNOS5 SPI

The naming EXYNOS4 is changed to EXYNOS for using shared SPI
config of EXYNOS4 and EXYNOS5. And S3C64XX_DEV_SPIn configs
are added to MACH_SMDK5250 config to use SPI on the EYXNOS5250.

Signed-off-by: Kyoungil Kim <ki0351.kim@samsung.com>
[kgene.kim@samsung.com: updated because of non-existing config]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>