Convert CONFIG_TEGRA_NAND to Kconfig

This converts the following to Kconfig:
   CONFIG_TEGRA_NAND

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/colibri_t20_defconfig b/configs/colibri_t20_defconfig
index b56b00d..b883fc1 100644
--- a/configs/colibri_t20_defconfig
+++ b/configs/colibri_t20_defconfig
@@ -22,7 +22,6 @@
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
-CONFIG_CMD_NAND=y
 CONFIG_CMD_USB=y
 CONFIG_CMD_USB_MASS_STORAGE=y
 # CONFIG_CMD_NFS is not set
@@ -49,6 +48,7 @@
 CONFIG_MTD=y
 CONFIG_DM_MTD=y
 CONFIG_MTD_RAW_NAND=y
+CONFIG_TEGRA_NAND=y
 CONFIG_SYS_NAND_ONFI_DETECTION=y
 CONFIG_MTD_UBI_FASTMAP=y
 CONFIG_DM_PMIC=y