prechecks: remove the docker max version check

Remove the docker max version check since we are not pinning
docker version any more.

Partially-Implements: blueprint precheck-tasks
Change-Id: Icfa10e72c56092931aae016afaeed4c6ce8cb337

ansible/roles/prechecks/tasks/service_checks.yml

@@ -10,4 +10,3 @@
   register: result
   failed_when: result | failed
                or (result.stdout | from_yaml).Server.Version | regex_replace('(\\d+\\.\\d+\\.\\d+).*', '\\1') | version_compare(docker_version_min, '<')
-               or (result.stdout | from_yaml).Server.Version | regex_replace('(\\d+\\.\\d+\\.\\d+).*', '\\1') | version_compare(docker_version_max, '>')

ansible/roles/prechecks/vars/main.yml

 docker_version_min: '1.6.0'
-docker_version_max: '1.8.2'
 docker_py_version_min: '1.2.0'