package/docker-engine: add CPE variables

cpe:2.3:a:docker:docker is a valid CPE identifier for this package:

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

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit b59ebb66f35ed79dcd07068dd5bd101c44ad6248)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/docker-engine/docker-engine.mk

@@ -13,6 +13,9 @@ DOCKER_ENGINE_LICENSE_FILES = LICENSE
 DOCKER_ENGINE_DEPENDENCIES = host-pkgconf
 DOCKER_ENGINE_GOMOD = github.com/docker/docker
 
+DOCKER_ENGINE_CPE_ID_VENDOR = docker
+DOCKER_ENGINE_CPE_ID_PRODUCT = docker
+
 DOCKER_ENGINE_LDFLAGS = \
 	-X $(DOCKER_ENGINE_GOMOD)/dockerversion.BuildTime="" \
 	-X $(DOCKER_ENGINE_GOMOD)/dockerversion.GitCommit="buildroot" \