card: Display if KDF is enabled or not.
* g10/call-agent.h (kdf_do_enabled): New field. * g10/call-agent.c (learn_status_cb): Set kdf_do_enabled if available. * g10/card-util.c (current_card_status): Inform the availability.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>