gpg: Remove the edit-key toggle command.

* g10/keyedit.c (cmds): Remove helptext from "toggle".
(keyedit_menu): Remove "toggle" var and remove the sub/pub check
against toggle.

Because it is now easily possible to have only secret keys for some of
the main/subkeys the current check on whether any secret is available
is not really useful. A finer grained check should eventually be
implemented.

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