make: Use consistent Docker tag for dev-docker-image
make: Use consistent Docker tag for dev-docker-image

This commit fixes the dev-docker-image make target to tag the Docker
image with the same tag as used in the subsequent 'docker push' command
given to the user.

Signed-off-by: Paul Chaignon <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>

cilium/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium,michi-covalent/cilium,tgraf/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium