python: Correct arguments number for migrateSetMaxSpeed
python: Correct arguments number for migrateSetMaxSpeed

The API definition accepts "flags" argument, however, the
implementation ignores it, though "flags" is unused currently,
we should expose it instead of hard coding, the API
implementation inside hypervisor driver is responsible to check
if the passed "flags" is valid.

libvirt/libvirt-python,cardoe/libvirt-python,libvirt/libvirt-python,cardoe/libvirt-python,libvirt/libvirt-python,cardoe/libvirt-python