Fix invalid property during test_technology_check_property

test_technology_check_property fails with:

bin/connman-test.sh: 71: Invalid property TetheringFreq: not found

ConnMan adds a new property to its Technologies.

https://phabricator.apertis.org/T8599

Signed-off-by: Frédéric Danis frederic.danis@collabora.com