scd: Clear CHV status on timeout error.
* scd/app-openpgp.c (clear_chv_status): New. (do_change_pin): Use clear_chv_status. (do_sign): Call clear_chv_status on GPG_ERR_TIMEOUT. (do_auth, do_decipher): Likewise.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>