scd: Disable pinpad if it's impossible by KDF DO.
* scd/app-openpgp.c (struct app_local_s): Add pinpad.disabled field. (do_getattr): Set pinpad.disabled field. (check_pinpad_request): Use the pinpad.disabled field. (do_setattr): Update pinpad.disabled field.
(cherry picked from commit 95c7498b76231d3297541172d878f6a26702539b)
- GnuPG-bug-id: T4832
- Signed-off-by: Werner Koch <wk@gnupg.org>