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>

package/libffi/libffi.mk

@@ -6,7 +6,6 @@
 
 LIBFFI_VERSION = 3.3
 LIBFFI_SITE = $(call github,libffi,libffi,v$(LIBFFI_VERSION))
-LIBFFI_CPE_ID_VERSION = 3.3
 LIBFFI_CPE_ID_UPDATE = rc0
 LIBFFI_LICENSE = MIT
 LIBFFI_LICENSE_FILES = LICENSE