Only show EzTune tab when platform is multirotor

The PR only shows the Ez Tune tab when the platform is either `PLATFORM_MULTIROTOR ` or `PLATFORM_TRICOPTER`. More platforms can be added in the function in main.js.

When changing the mixer to a non-supported platform. Ez Tune is automatically disabled.

js/serial_backend.js

@@ -257,6 +257,7 @@ function onValidFirmware()
 
                 $('#tabs ul.mode-connected .tab_setup a').click();
 
+                updateEzTuneTabVisibility(true);
                 updateFirmwareVersion();
             });
         });