mmc: dw_mmc: add missing MFD_SYSCON dependency for SOCFPGA

Added missing MFD_SYSCON dependency for SOCFPGA in order to fix
the following link error.

drivers/mmc/host/dw_mmc-socfpga.c:49: undefined reference to `syscon_regmap_lookup_by_compatible'
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Acked-by: NJaehoon Chung <jh80.chung@samsung.com>
Acked-by: NSeungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

drivers/mmc/host/Kconfig

@@ -569,7 +569,7 @@ config MMC_DW_EXYNOS
 
 config MMC_DW_SOCFPGA
 	tristate "SOCFPGA specific extensions for Synopsys DW Memory Card Interface"
-	depends on MMC_DW
+	depends on MMC_DW && MFD_SYSCON
 	select MMC_DW_PLTFM
 	help
 	  This selects support for Altera SoCFPGA specific extensions to the