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/imx6q_logic_defconfig b/configs/imx6q_logic_defconfig
index b4e1dbb..f0974bf 100644
--- a/configs/imx6q_logic_defconfig
+++ b/configs/imx6q_logic_defconfig
@@ -24,6 +24,7 @@
 CONFIG_MTDIDS_DEFAULT="nand0=gpmi-nand"
 CONFIG_MTDPARTS_DEFAULT="mtdparts=gpmi-nand:4m(uboot),1m(env),16m(kernel),1m(dtb),-(fs)"
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
 CONFIG_SYS_I2C_MXC=y
 CONFIG_FSL_ESDHC=y
 CONFIG_NAND=y