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/BSC9131RDB_NAND_SYSCLK100_defconfig b/configs/BSC9131RDB_NAND_SYSCLK100_defconfig
index 6e8ab27..feaa426 100644
--- a/configs/BSC9131RDB_NAND_SYSCLK100_defconfig
+++ b/configs/BSC9131RDB_NAND_SYSCLK100_defconfig
@@ -7,7 +7,7 @@
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
-CONFIG_SYS_EXTRA_OPTIONS="NAND,SYS_CLK_100"
+CONFIG_SYS_EXTRA_OPTIONS="SYS_CLK_100"
 CONFIG_ENV_IS_IN_NAND=y
 CONFIG_BOOTDELAY=10
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
@@ -26,6 +26,7 @@
 CONFIG_CMD_MTDPARTS=y
 CONFIG_FSL_CAAM=y
 # CONFIG_MMC is not set
+CONFIG_NAND=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_PHYLIB=y