Further set_mode cleanup
Further set_mode cleanup

Use the dedicated adapter_remove_discov_timeout function and don't care
about sessions when setting the discoverable timer since sessions can't
own the discoverable mode anymore.

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