imx:mx6slevk: change CONFIG_SYS_FSL_ESDHC_ADDR

Define CONFIG_SYS_FSL_ESDHC_ADDR using USDHC2_BASE_ADDR which is
used in board_mmc_init.
Signed-off-by: NPeng Fan <Peng.Fan@freescale.com>

include/configs/mx6slevk.h

@@ -40,7 +40,7 @@
 /* MMC Configs */
 #define CONFIG_FSL_ESDHC
 #define CONFIG_FSL_USDHC
-#define CONFIG_SYS_FSL_ESDHC_ADDR	0
+#define CONFIG_SYS_FSL_ESDHC_ADDR	USDHC2_BASE_ADDR
 
 #define CONFIG_MMC
 #define CONFIG_CMD_MMC