Fix to ensure that tacacs servers are ordered (reverse) by priority i…

…n pam.d's config. (#3322)

Present: Servers are listed in the same order as in redis-db
Fix: Save the sort o/p, hence use sorted list to write into pam.d's conf.
     As well convert priority to integer for use by sort.

files/image_config/hostcfgd/hostcfgd

@@ -114,7 +114,7 @@ class AaaCfg(object):
                 server['ip'] = addr
                 server.update(self.tacplus_servers[addr])
                 servers_conf.append(server)
-            sorted(servers_conf, key=lambda t: t['priority'], reverse=True)
+            servers_conf = sorted(servers_conf, key=lambda t: int(t['priority']), reverse=True)
 
         template_file = os.path.abspath(PAM_AUTH_CONF_TEMPLATE)
         env = jinja2.Environment(loader=jinja2.FileSystemLoader('/'), trim_blocks=True)