arm: socfpga: Enable saveenv for SD/MMC

Enable the able to save the environment variables when SD/MMC is used.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
diff --git a/include/configs/socfpga_sockit.h b/include/configs/socfpga_sockit.h
index 747e988..6c71ef4 100644
--- a/include/configs/socfpga_sockit.h
+++ b/include/configs/socfpga_sockit.h
@@ -59,6 +59,10 @@
 
 #endif
 
+#define CONFIG_ENV_IS_IN_MMC
+#define CONFIG_SYS_MMC_ENV_DEV		0	/* device 0 */
+#define CONFIG_ENV_OFFSET		512	/* just after the MBR */
+
 /* USB */
 #ifdef CONFIG_CMD_USB
 #define CONFIG_USB_DWC2_REG_ADDR	SOCFPGA_USB1_ADDRESS