Migrate CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG to Kconfig

Convert CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG to Kconfig

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Petr Vorel <petr.vorel@gmail.com>
Reviewed-by: Petr Vorel <petr.vorel at gmail.com>
diff --git a/configs/am335x_evm_norboot_defconfig b/configs/am335x_evm_norboot_defconfig
index 176c820..068c3f2 100644
--- a/configs/am335x_evm_norboot_defconfig
+++ b/configs/am335x_evm_norboot_defconfig
@@ -18,6 +18,7 @@
 CONFIG_MTDIDS_DEFAULT="nor0=physmap-flash.0"
 CONFIG_MTDPARTS_DEFAULT="mtdparts=physmap-flash.0:512k(u-boot),128k(u-boot-env1),128k(u-boot-env2),4m(kernel),-(rootfs)"
 CONFIG_ENV_IS_IN_FLASH=y
+CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
 CONFIG_DFU_MMC=y
 CONFIG_DFU_RAM=y
 CONFIG_MMC_OMAP_HS=y