obexd: Simplify code for calling mime driver flush()
obexd: Simplify code for calling mime driver flush()

OBEX_EV_REQ is the last thing that we are going to receive on PUT and
this is always going to be delivered. As the service driver will start
receiving data at or before its .put(), we can simply call flush() after
that. This also makes flush() usable in PUTs without length header.

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