virttest.qemu_devices: Supress pylint warning

The methods hotplug and verify_hotplug are called
correctly in the inherited classes.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
virttest.ppm_utils: Replace conditional expressions

They are not present in python 2.4. Replace them with
equivalent, py 2.4 compatible constructs.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>