support/testing: fix code style

Fix the trivial warnings from flake8:
 - remove modules imported but unused;
 - use 2 lines before class or module level method;
 - remove blank line at end of file.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

support/testing/run-tests

@@ -7,6 +7,7 @@ import multiprocessing
 
 from infra.basetest import BRTest
 
+
 def main():
     parser = argparse.ArgumentParser(description='Run Buildroot tests')
     parser.add_argument('testname', nargs='*',
@@ -116,5 +117,6 @@ def main():
 
     nose2.discover(argv=nose2_args)
 
+
 if __name__ == "__main__":
     sys.exit(main())