imx8mm_beacon: Enable HS400 on MMC controller

The i.MX8MM is capable of HS400.  Enable it in both
U-Boot and SPL for faster throughput.

Signed-off-by: Adam Ford <aford173@gmail.com>
diff --git a/configs/imx8mm_beacon_defconfig b/configs/imx8mm_beacon_defconfig
index c5d331f..49d5453 100644
--- a/configs/imx8mm_beacon_defconfig
+++ b/configs/imx8mm_beacon_defconfig
@@ -70,6 +70,13 @@
 CONFIG_SYS_I2C_MXC=y
 CONFIG_DM_MMC=y
 CONFIG_SUPPORT_EMMC_BOOT=y
+CONFIG_MMC_IO_VOLTAGE=y
+CONFIG_SPL_MMC_IO_VOLTAGE=y
+CONFIG_MMC_UHS_SUPPORT=y
+CONFIG_SPL_MMC_UHS_SUPPORT=y
+CONFIG_MMC_HS400_ES_SUPPORT=y
+CONFIG_MMC_HS400_SUPPORT=y
+CONFIG_SPL_MMC_HS400_SUPPORT=y
 CONFIG_FSL_USDHC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_ATHEROS=y