Fix set default or fallback font string isn't picked up by lua_xgettext

frontend/apps/reader/modules/readerfont.lua

@@ -210,8 +210,7 @@ end
 function ReaderFont:makeDefault(face)
     if face then
         UIManager:show(MultiConfirmBox:new{
-            text = T( _([[Set %1 as default or fallback font? The fallback font ]] 
-                      ..[[displays characters not found in the active font.]]), face),
+            text = T( _("Set %1 as default or fallback font? The fallback font displays characters not found in the active font."), face),
             choice1_text = _("Default"),
             choice1_callback = function()
                 G_reader_settings:saveSetting("cre_font", face)