Fix memtest breakage

CFG_MEMTEST_START uses weird magic involving gd, which fails to
compile. Use hardcoded values instead (we actually know how much RAM
we have on board.)

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

include/configs/atstk1002.h

@@ -200,12 +200,8 @@
 #define CFG_PBSIZE			(CFG_CBSIZE + sizeof(CFG_PROMPT) + 16)
 #define CFG_LONGHELP			1
 
-#define CFG_MEMTEST_START						\
-	({ gd->bd->bi_dram[0].start; })
-#define CFG_MEMTEST_END							\
-	({								\
-		gd->bd->bi_dram[0].start + gd->bd->bi_dram[0].size;	\
-	})
+#define CFG_MEMTEST_START		CFG_SDRAM_BASE
+#define CFG_MEMTEST_END			(CFG_MEMTEST_START + 0x700000)
 #define CFG_BAUDRATE_TABLE { 115200, 38400, 19200, 9600, 2400 }
 
 #endif /* __CONFIG_H */