mmc: support hs400 enhanced strobe mode

eMMC 5.1+ supports HS400 Enhances Strobe mode without the need for
tuning procedure.
The flow is as following:
 - set HS_TIMIMG (Highspeed)
 - Host change freq to <= 52Mhz
 - set the bus width to Enhanced strobe and DDR8Bit(CMD6),
   EXT_CSD[183] = 0x86 instead of 0x80
 - set HS_TIMING to 0x3 (HS400)
 - Host change freq to <= 200Mhz
 - Host select HS400 enhanced strobe complete

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/drivers/mmc/mmc-uclass.c b/drivers/mmc/mmc-uclass.c
index 9327c83..8bf63bb 100644
--- a/drivers/mmc/mmc-uclass.c
+++ b/drivers/mmc/mmc-uclass.c
@@ -105,6 +105,23 @@
 }
 #endif
 
+#if CONFIG_IS_ENABLED(MMC_HS400_ES_SUPPORT)
+int dm_mmc_set_enhanced_strobe(struct udevice *dev)
+{
+	struct dm_mmc_ops *ops = mmc_get_ops(dev);
+
+	if (ops->set_enhanced_strobe)
+		return ops->set_enhanced_strobe(dev);
+
+	return -ENOTSUPP;
+}
+
+int mmc_set_enhanced_strobe(struct mmc *mmc)
+{
+	return dm_mmc_set_enhanced_strobe(mmc->dev);
+}
+#endif
+
 int mmc_of_parse(struct udevice *dev, struct mmc_config *cfg)
 {
 	int val;