Initialize PS_ON at startup

Marlin/Marlin_main.cpp

@@ -294,6 +294,10 @@ void setup_powerhold()
       WRITE(SUICIDE_PIN, HIGH);
    #endif
  #endif
+ #if (PS_ON_PIN > -1)
+   SET_OUTPUT(PS_ON_PIN);
+   WRITE(PS_ON_PIN, PS_ON_AWAKE);
+ #endif
 }
 
 void suicide()