obexd: Fix not responding to pbap GET when data is already cached
obexd: Fix not responding to pbap GET when data is already cached

When data is cached but no stream/body is set the driver .write is never
called so no response is generated.

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