scd:p15: Prepare AODF parsing for other authentication types.

* scd/app-p15.c (auth_type_t): New.
(struct aodf_object_s): Add field auth_type.
(read_ef_aodf): Distinguish between pin and authkey types.  Include
the authtype in the verbose mode diags.

Note that the bulk of chnages are just indentation chnages. There
should be no functional change.

• Signed-off-by: Werner Koch <wk@gnupg.org>