corenet_ds: Update CONFIG_SYS_GBL_DATA_SIZE to deal with growth in gd_t

The recent change the env code added an additional 32 bytes into gd_t
and that causes to grow pass the previous CONFIG_SYS_GBL_DATA_SIZE size.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

include/configs/corenet_ds.h

@@ -213,7 +213,7 @@
 #endif
 #define CONFIG_SYS_INIT_RAM_END		0x00004000	/* End of used area in RAM */
 
-#define CONFIG_SYS_GBL_DATA_SIZE	128	/* num bytes initial data */
+#define CONFIG_SYS_GBL_DATA_SIZE	256	/* num bytes initial data */
 #define CONFIG_SYS_GBL_DATA_OFFSET	(CONFIG_SYS_INIT_RAM_END - CONFIG_SYS_GBL_DATA_SIZE)
 #define CONFIG_SYS_INIT_SP_OFFSET	CONFIG_SYS_GBL_DATA_OFFSET