arm: socfpga: Consolidate SDMMC environment

Remove the duplication of SDMMC environment configuration
from each boards' configuration header file into
socfpga_common.h
Signed-off-by: NChin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Dinh Nguyen <dinh.linux@gmail.com>
Cc: Pavel Machek <pavel@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Stefan Roese <sr@denx.de>

include/configs/socfpga_common.h

@@ -270,6 +270,12 @@ unsigned int cm_get_qspi_controller_clk_hz(void);
 #define CONFIG_SYS_CONSOLE_ENV_OVERWRITE
 #define CONFIG_ENV_SIZE			4096
 
+/* Environment for SDMMC boot */
+#if defined(CONFIG_ENV_IS_IN_MMC) && !defined(CONFIG_ENV_OFFSET)
+#define CONFIG_SYS_MMC_ENV_DEV		0	/* device 0 */
+#define CONFIG_ENV_OFFSET		512	/* just after the MBR */
+#endif
+
 /*
  * SPL
  *