spi: Kconfig: Add EXYNOS_SPI entry

Added EXYNOS_SPI entry on Kconfig with help description.

Signed-off-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index e4a90e8..d5e6881 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -29,6 +29,13 @@
 	  access the SPI NOR flash on platforms embedding this Designware
 	  IP core.
 
+config EXYNOS_SPI
+	bool "Samsung Exynos SPI driver"
+	help
+	  Enable the Samsung Exynos SPI driver. This driver can be used to
+	  access the SPI NOR flash on platforms embedding this Samsung
+	  Exynos IP core.
+
 config FSL_DSPI
 	bool "Freescale DSPI driver"
 	help