agent: Extend agent_card_getattr with KEYGRIP.
* agent/agent.h (struct card_key_info_s): KEYGRIP null terminated. (agent_card_getattr): Add KEYGRIP argument. * agent/call-scd.c (agent_card_getattr): Handle KEYGRIP argument. (card_keyinfo_cb): Make KEYGRIP null terminated. * agent/command.c (cmd_readkey): Follow the change.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>