Convert CONFIG_NAND_LPC32XX_SLC to Kconfig

This converts the following to Kconfig:
   CONFIG_NAND_LPC32XX_SLC

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/devkit3250_defconfig b/configs/devkit3250_defconfig
index 14c24ce..8a37122 100644
--- a/configs/devkit3250_defconfig
+++ b/configs/devkit3250_defconfig
@@ -34,6 +34,7 @@
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_NAND=y
+CONFIG_NAND_LPC32XX_SLC=y
 CONFIG_SPL_NAND_SIMPLE=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_ADDR_ENABLE=y
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index bdc2721..dad5711 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -31,6 +31,11 @@
 	  of OOB area before last ECC sector data starts.  This is potentially
 	  used to preserve the bad block marker in the OOB area.
 
+config NAND_LPC32XX_SLC
+	bool "Support LPC32XX_SLC controller"
+	help
+	  Enable the LPC32XX SLC NAND controller.
+
 config NAND_OMAP_GPMC
 	bool "Support OMAP GPMC NAND controller"
 	depends on ARCH_OMAP2PLUS
diff --git a/include/configs/devkit3250.h b/include/configs/devkit3250.h
index d12f371..00e9c44 100644
--- a/include/configs/devkit3250.h
+++ b/include/configs/devkit3250.h
@@ -84,7 +84,6 @@
 /*
  * NAND controller
  */
-#define CONFIG_NAND_LPC32XX_SLC
 #define CONFIG_SYS_NAND_BASE		SLC_NAND_BASE
 #define CONFIG_SYS_MAX_NAND_DEVICE	1
 #define CONFIG_SYS_NAND_BASE_LIST	{ CONFIG_SYS_NAND_BASE }
diff --git a/scripts/config_whitelist.txt b/scripts/config_whitelist.txt
index 8d1b03e..ed90cfa 100644
--- a/scripts/config_whitelist.txt
+++ b/scripts/config_whitelist.txt
@@ -1380,7 +1380,6 @@
 CONFIG_NAND_KIRKWOOD
 CONFIG_NAND_KMETER1
 CONFIG_NAND_LPC32XX_MLC
-CONFIG_NAND_LPC32XX_SLC
 CONFIG_NAND_MODE_REG
 CONFIG_NAND_MXC_V1_1
 CONFIG_NAND_OMAP_ECCSCHEME