python: Use range() instead of xrange()

python: Use range() instead of xrange()

Python 2 has a range() function which returns a list, and an xrange()
one which returns an iterator.

Python 3 lost the function returning a list, and renamed the function
returning an iterator as range().

As a result, using range() makes the scripts compatible with both Python
versions 2 and 3.

Signed-off-by: Mathieu Bridon <bochecha@daitauha.fr>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>