gpg: Repurpose the ISO defined DO "sex" to "salutation".

* g10/card-util.c (current_card_status): String changes.
(change_sex): Description change.
(cmds): Add "salutation"; keep "sex" as an alias.

Note that we can't change the used values or tags but at least the UI
should show reflect the real purpose of the field.

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