Remove timesync_interval default of 1h.

The MuxTime (see previous commit) is preferred for (not so accurate)
time synchronization. We might want to update (or remove) the timesync
implementation, as it calculates the GPS time at the time of receiving
at the server, rather than at the gateway.

cmd/chirpstack-gateway-bridge/cmd/root.go

@@ -47,7 +47,6 @@ func init() {
 	viper.SetDefault("backend.basic_station.bind", ":3001")
 	viper.SetDefault("backend.basic_station.stats_interval", time.Second*30)
 	viper.SetDefault("backend.basic_station.ping_interval", time.Minute)
-	viper.SetDefault("backend.basic_station.timesync_interval", time.Hour)
 	viper.SetDefault("backend.basic_station.read_timeout", time.Minute+(5*time.Second))
 	viper.SetDefault("backend.basic_station.write_timeout", time.Second)
 	viper.SetDefault("backend.basic_station.region", "EU868")