sandbox: Add 64-bit sandbox

To debug device tree issues involving 32- and 64-bit platforms, it is useful to
have a generic 64-bit platform available.

Add a version of the sandbox that uses 64-bit integers for its physical
addresses as well as a modified device tree.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Added CONFIG_SYS_TEXT_BASE to configs/sandbox64_defconfig
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/fdtdec.h b/include/fdtdec.h
index 4afb9ac..4153a6a 100644
--- a/include/fdtdec.h
+++ b/include/fdtdec.h
@@ -24,7 +24,7 @@
 typedef phys_addr_t fdt_addr_t;
 typedef phys_size_t fdt_size_t;
 #ifdef CONFIG_PHYS_64BIT
-#define FDT_ADDR_T_NONE (-1ULL)
+#define FDT_ADDR_T_NONE (-1U)
 #define fdt_addr_to_cpu(reg) be64_to_cpu(reg)
 #define fdt_size_to_cpu(reg) be64_to_cpu(reg)
 typedef fdt64_t fdt_val_t;