Added mutex for link and pagebutton for version 2.2
Added mutex for link and pagebutton for version 2.2

roman1528/fhem-tablet-ui,viegener/fhem-tablet-ui,roman1528/fhem-tablet-ui,knowthelist/fhem-tablet-ui,roman1528/fhem-tablet-ui,viegener/fhem-tablet-ui,knowthelist/fhem-tablet-ui,roman1528/fhem-tablet-ui,viegener/fhem-tablet-ui,knowthelist/fhem-tablet-ui,knowthelist/fhem-tablet-ui,viegener/fhem-tablet-ui,knowthelist/fhem-tablet-ui