package/libffi: drop superfluous CPE_ID_VERSION

The default for FOO_CPE_ID_VERSION is to default to FOO_VERSION, so drop
this superfluous definition.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Cc: "Weber, Matthew L Collins" <Matthew.Weber@collins.com>
Reviewed-by: Matthew Weber <Matthew.Weber@collins.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>