setUp() is used to populate a directory of temporary files, and deleted in
__del__. However setUp() is called once *per test* so __del__ would only be
able to remove the last directory created.
Fix the code by using the natural counterpart to setUp, tearDown(), to clean up.
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
