spi: s3c64xx: Allow build on all Samsung platforms

Replace all symbols by simple dependency PLAT_SAMSUNG.

Signed-off-by: Mateusz Krawczuk <m.krawczuk@partner.samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/Kconfig

@@ -393,7 +393,7 @@ config SPI_S3C24XX_FIQ
 
 config SPI_S3C64XX
 	tristate "Samsung S3C64XX series type SPI"
-	depends on (ARCH_S3C24XX || ARCH_S3C64XX || ARCH_S5P64X0 || ARCH_EXYNOS)
+	depends on PLAT_SAMSUNG
 	select S3C64XX_DMA if ARCH_S3C64XX
 	help
 	  SPI driver for Samsung S3C64XX and newer SoCs.