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/trats_defconfig b/configs/trats_defconfig
index 019dca3..fde2b13 100644
--- a/configs/trats_defconfig
+++ b/configs/trats_defconfig
@@ -26,6 +26,7 @@
 # CONFIG_CMD_MISC is not set
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_OF_CONTROL=y
+CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
 CONFIG_DFU_MMC=y
 CONFIG_DM_I2C_GPIO=y
 CONFIG_SYS_I2C_S3C24X0=y