Add return in CustomFirmwarePlugin::hasGimbal

remove warning caused build failure

custom-example/src/FirmwarePlugin/CustomFirmwarePlugin.cc

@@ -52,4 +52,6 @@ bool CustomFirmwarePlugin::hasGimbal(Vehicle* /*vehicle*/, bool& rollSupported,
     rollSupported = false;
     pitchSupported = true;
     yawSupported = true;
+
+    return true;
 }