In python 3.x the iteritems() method has been removed from dictionaries,
and the items() method does effectively the same thing. On python 2.x
using items() is a little less efficient since it involves copying data,
but as speed isn't a concern in the affected code switch to using
items() anyway for simplicity.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Simon Glass <sjg@chromium.org>