package/libspdm: add LIBSPDM_CPE_ID_VENDOR

cpe:2.3:a:dmtf:libspdm is a valid CPE identifier for this package:

  https://nvd.nist.gov/products/cpe/search/results?namingFormat=2.3&keyword=cpe%3A2.3%3Aa%3Admtf%3Alibspdm

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libspdm/libspdm.mk

@@ -8,6 +8,7 @@ LIBSPDM_VERSION = 3.0.0
 LIBSPDM_SITE = $(call github,DMTF,libspdm,$(LIBSPDM_VERSION))
 LIBSPDM_LICENSE = BSD-3-Clause
 LIBSPDM_LICENSE_FILES = LICENSE.md
+LIBSPDM_CPE_ID_VENDOR = dmtf
 
 LIBSPDM_INSTALL_STAGING = YES
 LIBSPDM_INSTALL_TARGET = NO