Prevent oFono watchlist crash in unregister when spn_watches already deleted

Signed-off-by: Miia Leinonen <miia.leinonen@oss.tieto.com>
Prevent oFono watchlist crash in unregister when spn_watches already deleted

Signed-off-by: Miia Leinonen <miia.leinonen@oss.tieto.com>
Merge branch 'master' of https://github.com/leinomii/ofono into oma_ofono9675
Merge branch 'oma_ofono9675'