support/testing: fix code style in emulator

Remove unused import.
Use 2 empty lines before a class.
Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/testing/infra/emulator.py

 import pexpect
 
 import infra
-import infra.basetest
+
 
 class Emulator(object):