imx: imx8ulp_evk: Enable SD/MMC port auto detect

Enable the SD/MMC port auto detect.
The mmc relevant env can be reset when auto detect is enabled.

Signed-off-by: Peng Fan <peng.fan@nxp.com>

board/freescale/imx8ulp_evk/imx8ulp_evk.c

@@ -127,5 +127,8 @@ int board_early_init_f(void)
 
 int board_late_init(void)
 {
+#if CONFIG_IS_ENABLED(ENV_IS_IN_MMC)
+	board_late_mmc_env_init();
+#endif
 	return 0;
 }