Make bootscreen configurable for the graphic displays

Saves about 473 byte of progmem and 28 bytes of RAM.

Marlin/Marlin_main.cpp

@@ -666,7 +666,6 @@ void setup() {
   Config_RetrieveSettings();
 
   lcd_init();
-  _delay_ms(1000);  // wait 1sec to display the splash screen
 
   tp_init();    // Initialize temperature loop
   plan_init();  // Initialize planner;