Based on Jouni Malinen's [76055b4c6 "tests: D-Bus Get/Set Pmf"], modified
to use the correct "s" signature for the "Pmf" property.
Removed the negative test cases, because the synthesized property doens't
seem to do error checking upon being set.
Signed-off-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>