gatttool: Remove extra reference to the connection IO Channel
gatttool: Remove extra reference to the connection IO Channel

As we want the connection to be closed when the last GAttrib
reference is dropped, we don't need to keep this reference.

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