imx8mq_evk: Move CONFIG_ENV_IS_IN_MMC to Kconfig

Currently the command "saveenv" is not available.

The CONFIG_ENV_IS_IN_MMC symbol has been converted to Kconfig,
so fix the problem by moving it to the defconfig.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/imx8mq_evk_defconfig b/configs/imx8mq_evk_defconfig
index 68656b0..46100b6 100644
--- a/configs/imx8mq_evk_defconfig
+++ b/configs/imx8mq_evk_defconfig
@@ -22,6 +22,7 @@
 CONFIG_CMD_FAT=y
 CONFIG_OF_CONTROL=y
 CONFIG_DEFAULT_DEVICE_TREE="fsl-imx8mq-evk"
+CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SAVED_DRAM_TIMING_BASE=0x40000000
 CONFIG_DM_GPIO=y
 CONFIG_DM_I2C=y
diff --git a/include/configs/imx8mq_evk.h b/include/configs/imx8mq_evk.h
index f043022..a9e38a7 100644
--- a/include/configs/imx8mq_evk.h
+++ b/include/configs/imx8mq_evk.h
@@ -187,7 +187,6 @@
 #define CONFIG_ENV_OVERWRITE
 #define CONFIG_ENV_OFFSET               (64 * SZ_64K)
 #define CONFIG_ENV_SIZE			0x1000
-#define CONFIG_ENV_IS_IN_MMC
 #define CONFIG_SYS_MMC_ENV_DEV		1   /* USDHC2 */
 #define CONFIG_MMCROOT			"/dev/mmcblk1p2"  /* USDHC2 */