imx: mx6sxsabresd: enlarge ENV offset

The u-boot-dtb.imx size is about 519KB, so 8 * 64KB conflicts
with u-boot-dtb.imx. Enlarge the offset to 14 * 64KB to fix it.
Signed-off-by: NPeng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>

include/configs/mx6sxsabresd.h

@@ -203,7 +203,7 @@
 #endif
 #endif
 
-#define CONFIG_ENV_OFFSET		(8 * SZ_64K)
+#define CONFIG_ENV_OFFSET		(14 * SZ_64K)
 #define CONFIG_ENV_SIZE			SZ_8K
 
 #define CONFIG_SYS_FSL_USDHC_NUM	3