malta: Allow MIPS64 builds

Both real Malta boards & emulators that mimic Malta (eg. QEMU) can
support MIPS64 CPUs. Allow MIPS64 builds of U-Boot for such boards,
which enables the user to make use of the whole 64 bit address space.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
diff --git a/include/configs/malta.h b/include/configs/malta.h
index a369678..fc4baba 100644
--- a/include/configs/malta.h
+++ b/include/configs/malta.h
@@ -39,14 +39,18 @@
  */
 #define CONFIG_SYS_MONITOR_BASE		CONFIG_SYS_TEXT_BASE
 
-#define CONFIG_SYS_SDRAM_BASE		0x80000000 /* Cached addr */
+#ifdef CONFIG_64BIT
+# define CONFIG_SYS_SDRAM_BASE		0xffffffff80000000
+#else
+# define CONFIG_SYS_SDRAM_BASE		0x80000000
+#endif
 #define CONFIG_SYS_MEM_SIZE		(256 * 1024 * 1024)
 
 #define CONFIG_SYS_INIT_SP_OFFSET	0x400000
 
-#define CONFIG_SYS_LOAD_ADDR		0x81000000
-#define CONFIG_SYS_MEMTEST_START	0x80100000
-#define CONFIG_SYS_MEMTEST_END		0x80800000
+#define CONFIG_SYS_LOAD_ADDR		(CONFIG_SYS_SDRAM_BASE + 0x01000000)
+#define CONFIG_SYS_MEMTEST_START	(CONFIG_SYS_SDRAM_BASE + 0x00100000)
+#define CONFIG_SYS_MEMTEST_END		(CONFIG_SYS_SDRAM_BASE + 0x00800000)
 
 #define CONFIG_SYS_MALLOC_LEN		(128 * 1024)
 #define CONFIG_SYS_BOOTPARAMS_LEN	(128 * 1024)
@@ -69,7 +73,11 @@
 /*
  * Flash configuration
  */
-#define CONFIG_SYS_FLASH_BASE		0xbe000000
+#ifdef CONFIG_64BIT
+# define CONFIG_SYS_FLASH_BASE		0xffffffffbe000000
+#else
+# define CONFIG_SYS_FLASH_BASE		0xbe000000
+#endif
 #define CONFIG_SYS_MAX_FLASH_BANKS	1
 #define CONFIG_SYS_MAX_FLASH_SECT	128
 #define CONFIG_SYS_FLASH_CFI