device_tree: Increase FDT_MAX_SIZE to 1 MiB

It is not uncommon for a contemporary FDT to be larger than 64 KiB,
leading to failures loading the device tree from sysfs:

    qemu-system-aarch64: qemu_fdt_setprop: Couldn't set ...: FDT_ERR_NOSPACE

Hence increase the limit to 1 MiB, like on PPC.

For reference, the largest arm64 DTB created from the Linux sources is
ca. 75 KiB large (100 KiB when built with symbols/fixup support).

Cc: qemu-stable@nongnu.org
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Message-id: 1523541337-23919-1-git-send-email-geert+renesas@glider.be
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

device_tree.c

@@ -29,7 +29,7 @@
 
 #include <libfdt.h>
 
-#define FDT_MAX_SIZE  0x10000
+#define FDT_MAX_SIZE  0x100000
 
 void *create_device_tree(int *sizep)
 {