powerpc/mpc85xx:Update MONITOR_LEN for 768KB u-boot size

U-boot binary size has been increased from 512KB to 768KB.

So update CONFIG_SYS_MONITOR_LEN to reflect the same.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/include/configs/corenet_ds.h b/include/configs/corenet_ds.h
index ca14558..db6b9be 100644
--- a/include/configs/corenet_ds.h
+++ b/include/configs/corenet_ds.h
@@ -310,7 +310,7 @@
 #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_INIT_RAM_SIZE - GENERATED_GBL_DATA_SIZE)
 #define CONFIG_SYS_INIT_SP_OFFSET	CONFIG_SYS_GBL_DATA_OFFSET
 
-#define CONFIG_SYS_MONITOR_LEN		(512 * 1024)
+#define CONFIG_SYS_MONITOR_LEN		(768 * 1024)
 #define CONFIG_SYS_MALLOC_LEN		(1024 * 1024)	/* Reserved for malloc */
 
 /* Serial Port - controlled on board with jumper J8