client: Fix data growth if reconfiguring ad service

Since commit 65eff5c2 ("client: Rename set-service to service"), data
are appended in every run of advertise service with data arguments as
below:

  [bluetooth]# service 1 1 2
  [bluetooth]# service
  UUID: SDP(1)
    01 02                                            ..
  [bluetooth]# service 1 1 2 3
  [bluetooth]# service
  UUID: SDP(1)
    01 02 01 02 03                                   .....
1 file changed