imx: mx6ulevk: change mtest memory size to 128M

To i.MX6UL 14x14 EVK, system memory is 512M; to i.MX6UL 9x9 EVK,
system memory is 256M. If setting mtest size to 256M, mtest will
crash uboot for i.MX6UL 9x9 evk. So change mtest size to 128M.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>

include/configs/mx6ul_14x14_evk.h

@@ -156,7 +156,7 @@
 /* Miscellaneous configurable options */
 #define CONFIG_CMD_MEMTEST
 #define CONFIG_SYS_MEMTEST_START	0x80000000
-#define CONFIG_SYS_MEMTEST_END		(CONFIG_SYS_MEMTEST_START + 0x10000000)
+#define CONFIG_SYS_MEMTEST_END		(CONFIG_SYS_MEMTEST_START + 0x8000000)
 
 #define CONFIG_SYS_LOAD_ADDR		CONFIG_LOADADDR
 #define CONFIG_SYS_HZ			1000