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/igep0032_defconfig b/configs/igep0032_defconfig
index 237bc43..e8c704e 100644
--- a/configs/igep0032_defconfig
+++ b/configs/igep0032_defconfig
@@ -31,6 +31,7 @@
 # CONFIG_CMD_UBIFS is not set
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_MMC_OMAP_HS=y
+CONFIG_NAND=y
 CONFIG_SYS_NS16550=y
 CONFIG_FAT_WRITE=y
 CONFIG_OF_LIBFDT=y