dtoc: Move the struct import into the correct order

This should be in with the other system includes. Move it.
Signed-off-by: NSimon Glass <sjg@chromium.org>

tools/dtoc/dtoc.py

@@ -9,6 +9,7 @@
 import copy
 from optparse import OptionError, OptionParser
 import os
+import struct
 import sys
 
 import fdt_util
@@ -29,8 +30,6 @@ except ImportError:
     from fdt_fallback import Fdt
     import fdt_fallback as fdt
 
-import struct
-
 # When we see these properties we ignore them - i.e. do not create a structure member
 PROP_IGNORE_LIST = [
     '#address-cells',