Updating elrepo URL to use major distribution variable

Signed-off-by: Lucas A. Wilson <luke.wilson@dell.com>

roles/common/vars/main.yml

@@ -42,7 +42,7 @@ accelerator_discovery_script_mode: 0755
 
 elrepo_gpg_key_url: https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
 
-elrepo_rpm_url: https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
+elrepo_rpm_url: "https://www.elrepo.org/elrepo-release-{{ ansible_facts['distribution_major_version'] }}.el{{ ansible_facts['distribution_major_version'] }}.elrepo.noarch.rpm" 
 
 docker_repo_url: https://download.docker.com/linux/centos/docker-ce.repo