Devkit8000: Fix build after introduction of GENERATED_GBL_DATA_SIZE

This patch fixes the issue by defining and using
CONFIG_SYS_INIT_RAM_SIZE and CONFIG_SYS_INIT_RAM_ADDR.

This patch adopts the
commit 31bfcf1c
from Steve Sakoman and Sandeep Paulraj on Devkit8000.
Signed-off-by: NThomas Weber <weber@corscience.de>

include/configs/devkit8000.h

@@ -308,6 +308,10 @@ extern unsigned int boot_flash_type;
 #endif
 
 #define CONFIG_SYS_SDRAM_BASE          PHYS_SDRAM_1
-#define CONFIG_SYS_INIT_SP_ADDR        (LOW_LEVEL_SRAM_STACK - CONFIG_SYS_GBL_DATA_SIZE)
+#define CONFIG_SYS_INIT_RAM_ADDR        0x4020f800
+#define CONFIG_SYS_INIT_RAM_SIZE        0x800
+#define CONFIG_SYS_INIT_SP_ADDR         (CONFIG_SYS_INIT_RAM_ADDR + \
+		                                         CONFIG_SYS_INIT_RAM_SIZE - \
+		                                         GENERATED_GBL_DATA_SIZE)
 
 #endif /* __CONFIG_H */