nios2 - adjust gbl data off to account for bd_info

 * Adjust the GBL_DATA_OFFSET to account for the fact that we'll be
   using the space between that offset and the start of the malloc
   region to allocate both a gd structure and a board info structure.

 * This fixes a memory corruption bug due to overlap of the malloc
   region and the bd_info structure.
Signed-off-by: NAlex Hornung <alex@alexhornung.com>
Signed-off-by: NThomas Chou <thomas@wytron.com.tw>

include/configs/nios2-generic.h

@@ -131,7 +131,8 @@
 #define CONFIG_SYS_MALLOC_BASE		(CONFIG_SYS_MONITOR_BASE - \
 					 CONFIG_SYS_MALLOC_LEN)
 #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_MALLOC_BASE - \
-					 GENERATED_GBL_DATA_SIZE)
+					 GENERATED_GBL_DATA_SIZE - \
+					 GENERATED_BD_INFO_SIZE)
 #define CONFIG_SYS_INIT_SP		CONFIG_SYS_GBL_DATA_OFFSET
 
 /*