Fix not waiting mode change when setting powered property
Fix not waiting mode change when setting powered property

This may cause errors if the user application immediately set another
mode.

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