service: Fix calling Agent API request input function

service: Fix calling Agent API request input function

Requesting passphrases from the user has been done only when the
ConnectService D-Bus method has been called. As user input may be
needed every time a service is connected, input requesting moved to
__connman_service_connect() instead. Also to note is that the same
service can be retried after a failed connection attempt, for those
cases an already associated service->network needs to be disconnected
before an new connection is attempted.