configs: enable the CONFIG_DM_MMC for exynos4 series

Enable the CONFIG_DM_MMC for exynos4 series.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/configs/trats2_defconfig b/configs/trats2_defconfig
index 8c92f2f..16ac27f 100644
--- a/configs/trats2_defconfig
+++ b/configs/trats2_defconfig
@@ -37,6 +37,7 @@
 CONFIG_DFU_MMC=y
 CONFIG_DM_I2C_GPIO=y
 CONFIG_SYS_I2C_S3C24X0=y
+CONFIG_DM_MMC=y
 CONFIG_MMC_DW=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_SDMA=y