var: remove broadcast check to 0 and check just newer 255

There were both addresses used 0 as a subnet and 255 as broadcast
 but the former is no more used in el9. Removing it too.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=94c821c74bf5fe0c25e09df5334a16f98608db90
9 jobs for !841 with vb/remove_broadcast_to_0 in 2 minutes and 12 seconds
detached
Status Name Job ID Coverage
  Test
passed TestResults #13771149
manual

00:01:01

passed UnitTests #13771148

00:01:10

 
  External
failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-test-upstream/1902/

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-test-upstream/1903/

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-test-upstream/1907/

passed https://jenkins-networkmanager.apps.ocp.ci.centos.org/job/NetworkManager-test-mr/722/

00:30:53

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-test-upstream/1902/

02:58:48

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-test-upstream/1903/

00:56:42

failed https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-test-upstream/1907/

00:56:14