dtoc: Make integer division python 3.x safe

If we use the '/' operator then python 3.x will produce a float, and
refuse to multiply the string sequence in Conv_name_to_c by it with:

    TypeError: can't multiply sequence by non-int of type 'float'

Use the '//' operator instead to enforce that we want integer rather
than floating point division.
Signed-off-by: NPaul Burton <paul.burton@imgtec.com>
Acked-by: NSimon Glass <sjg@chromium.org>

tools/dtoc/dtoc.py

@@ -60,7 +60,7 @@ def Conv_name_to_c(name):
 def TabTo(num_tabs, str):
     if len(str) >= num_tabs * 8:
         return str + ' '
-    return str + '\t' * (num_tabs - len(str) / 8)
+    return str + '\t' * (num_tabs - len(str) // 8)
 
 class DtbPlatdata:
     """Provide a means to convert device tree binary data to platform data