drivers: spi: cf_spi: add Kconfig option

This patch adds cf_spi DM Kconfig option.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Angelo Dureghello <angelo@sysam.it>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index c3a829d..7044da3 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -87,6 +87,12 @@
 	  used to access the SPI NOR flash on platforms embedding this
 	  Cadence IP core.
 
+config CF_SPI
+        bool "ColdFire SPI driver"
+        help
+          Enable the ColdFire SPI driver. This driver can be used on
+          some m68k SoCs.
+
 config DESIGNWARE_SPI
 	bool "Designware SPI driver"
 	help