fix review comments (don't let commands queue up if we are missing a display)

src/screen.cpp

@@ -401,10 +401,7 @@ void _screen_header()
 }
 #endif
 
-Screen::Screen(uint8_t address, uint8_t sda, uint8_t scl)
-    : cmdQueue(32), useDisplay(false), dispdev(address, sda, scl), ui(&dispdev)
-{
-}
+Screen::Screen(uint8_t address, uint8_t sda, uint8_t scl) : cmdQueue(32), dispdev(address, sda, scl), ui(&dispdev) {}
 
 void Screen::handleSetOn(bool on)
 {