Blackfin: bf537-stamp: increase monitor size

The new jffs2 code pushed the code size just over the limit, so increase
the limit a bit more.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

include/configs/bf537-stamp.h

@@ -52,7 +52,7 @@
 #define CONFIG_EBIU_AMBCTL0_VAL	0x7BB07BB0
 #define CONFIG_EBIU_AMBCTL1_VAL	0xFFC27BB0
 
-#define CONFIG_SYS_MONITOR_LEN		(384 * 1024)
+#define CONFIG_SYS_MONITOR_LEN		(512 * 1024)
 #define CONFIG_SYS_MALLOC_LEN		(384 * 1024)