Convert CONFIG_NAND_OMAP_GPMC et al and CONFIG_NAND_MXC to Kconfig

This converts the following to Kconfig:
   CONFIG_NAND_MXC
   CONFIG_NAND_OMAP_GPMC
   CONFIG_NAND_OMAP_GPMC_PREFETCH
   CONFIG_NAND_OMAP_ELM
   CONFIG_SPL_NAND_AM33XX_BCH
   CONFIG_SPL_NAND_SIMPLE
   CONFIG_SYS_NAND_BUSWIDTH_16BIT

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
[trini: Finish migration of CONFIG_SPL_NAND_SIMPLE, fix some build issues,
        add CONFIG_NAND_MXC so we can do CONFIG_SYS_NAND_BUSWIDTH_16BIT]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/flea3_defconfig b/configs/flea3_defconfig
index 29da42c..04c5240 100644
--- a/configs/flea3_defconfig
+++ b/configs/flea3_defconfig
@@ -9,7 +9,6 @@
 CONFIG_SYS_PROMPT="flea3 U-Boot > "
 CONFIG_CMD_IMLS=y
 CONFIG_CMD_I2C=y
-CONFIG_CMD_NAND=y
 CONFIG_CMD_SPI=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_DHCP=y
@@ -20,6 +19,8 @@
 CONFIG_ENV_IS_IN_FLASH=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
+CONFIG_NAND=y
+CONFIG_NAND_MXC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
 CONFIG_OF_LIBFDT=y