arm: socfpga: Enable CONFIG_DM_MMC

Enable driver model MMC support on SoCFPGA.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/configs/socfpga_socrates_defconfig b/configs/socfpga_socrates_defconfig
index d391f46..932f0e8 100644
--- a/configs/socfpga_socrates_defconfig
+++ b/configs/socfpga_socrates_defconfig
@@ -21,3 +21,4 @@
 CONFIG_SYS_NS16550=y
 CONFIG_CADENCE_QSPI=y
 CONFIG_DESIGNWARE_SPI=y
+CONFIG_DM_MMC=y