gpg: Print sec/sbb with --import-option import-show or show-only.

* g10/import.c (import_one): Pass FROM_SK to list_keyblock_direct.

Note that this will likely add the suffix '#' top "sec" because the
secret key has not yet (or will not be) imported. If the secret key
already exists locally another suffix might be printed. The upshot is
that the suffix has no usefulness.

• GnuPG-bug-id: T3431
• Signed-off-by: Werner Koch <wk@gnupg.org>