agent: Fix double D-Bus message unref
agent: Fix double D-Bus message unref

Inside the g_dbus_send_message() we are already doing the
D-BUS message unref.

ComputeCycles/bluez,silent-snowman/bluez,silent-snowman/bluez,pkarasev3/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,mapfau/bluez,pkarasev3/bluez,mapfau/bluez,silent-snowman/bluez,ComputeCycles/bluez,ComputeCycles/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez