Included ansible_distribution_major_version #29561 (#31754)

Included ansible_distribution_major_version according with
issue #29561

lib/ansible/module_utils/facts/system/distribution.py

@@ -469,6 +469,7 @@ class Distribution(object):
         aix_facts = {}
         rc, out, err = self.module.run_command("/usr/bin/oslevel")
         data = out.split('.')
+        aix_facts['distribution_major_version'] = data[0]
         aix_facts['distribution_version'] = data[0]
         aix_facts['distribution_release'] = data[1]
         return aix_facts