scd: minor cleanup to merge other works.
* scd/iso7816.c (do_generate_keypair): Use const char * for DATA. (iso7816_generate_keypair, iso7816_read_public_key): Likewise. * scd/app-openpgp.c (get_public_key): Follow the change. (do_genkey): Ditto. Use ERR instead of RC. Use u32 for CREATED_AT.
Backport of master commit: f1845f25dbea79c191427710fa56ed01e63a045b
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>