Convert CONFIG_NAND to Kconfig

This converts the following to Kconfig:
   CONFIG_NAND

Signed-off-by: Adam Ford <aford173@gmail.com>
[trini: Sync up a few more, add imply's]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/igep0030_defconfig b/configs/igep0030_defconfig
index b80db9a..bd49181 100644
--- a/configs/igep0030_defconfig
+++ b/configs/igep0030_defconfig
@@ -39,6 +39,7 @@
 CONFIG_LED_STATUS_BOOT_ENABLE=y
 CONFIG_LED_STATUS_BOOT=0
 CONFIG_MMC_OMAP_HS=y
+CONFIG_NAND=y
 CONFIG_SYS_NS16550=y
 CONFIG_FAT_WRITE=y
 CONFIG_OF_LIBFDT=y