spi: s3c64xx: Allow driver to build if COMPILE_TEST is enabled

The driver only has runtime but no build time dependency with PLAT_SAMSUNG
|| ARCH_EXYNOS so it can be built for testing purposes if the COMPILE_TEST
option is enabled.

This is useful to have more build coverage and make sure that the driver
is not affected by changes that could cause build regressions.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -553,7 +553,7 @@ config SPI_S3C24XX_FIQ
 
 config SPI_S3C64XX
 	tristate "Samsung S3C64XX series type SPI"
-	depends on (PLAT_SAMSUNG || ARCH_EXYNOS)
+	depends on (PLAT_SAMSUNG || ARCH_EXYNOS || COMPILE_TEST)
 	help
 	  SPI driver for Samsung S3C64XX and newer SoCs.