rockchip: config: evb-rk3399: Add rockchip dwmmc support

This enable support for SD card on evb-rk3399.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/configs/evb-rk3399_defconfig b/configs/evb-rk3399_defconfig
index 509c86b..909c688 100644
--- a/configs/evb-rk3399_defconfig
+++ b/configs/evb-rk3399_defconfig
@@ -30,6 +30,7 @@
 CONFIG_SYS_I2C_ROCKCHIP=y
 CONFIG_MISC=y
 CONFIG_MMC_DW=y
+CONFIG_MMC_DW_ROCKCHIP=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_ROCKCHIP=y
 CONFIG_SF_DEFAULT_SPEED=20000000