imx: imx8mm_evk: Enable dynamic settings to mmcdev and mmcroot

Enable dynamic settings to mmcdev and mmcroot for i.MX8MM-EVK

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/board/freescale/imx8mm_evk/imx8mm_evk.c b/board/freescale/imx8mm_evk/imx8mm_evk.c
index 4c4436a..d41db8d 100644
--- a/board/freescale/imx8mm_evk/imx8mm_evk.c
+++ b/board/freescale/imx8mm_evk/imx8mm_evk.c
@@ -59,6 +59,9 @@
 
 int board_late_init(void)
 {
+	if (IS_ENABLED(CONFIG_ENV_IS_IN_MMC))
+		board_late_mmc_env_init();
+
 	if (IS_ENABLED(CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG)) {
 		env_set("board_name", "EVK");
 		env_set("board_rev", "iMX8MM");