* iso7816.h (iso7816_change_reference_data_kp): Remove arguments
of OLDCHV, OLDCHVLEN, NEWCHV, and NEWCHVLEN.
* iso7816.c (iso7816_change_reference_data_kp): Call
apdu_keypad_modify.
(iso7816_change_reference_data): Don't call
iso7816_change_reference_data_kp.
* apdu.h (apdu_keypad_modify): New.
* apdu.c (pcsc_keypad_modify, apdu_keypad_modify): New.
(struct reader_table_s): New memeber function keypad_modify.
(new_reader_slot, open_ct_reader, open_ccid_reader)
(open_rapdu_reader): Initialize keypad_modify.
* app-openpgp.c (do_change_pin): Handle keypad and call
iso7816_change_reference_data_kp if it is the case.