Small code tweaks re lcd.print

Marlin/dogm_lcd_implementation.h

@@ -222,7 +222,7 @@ static void lcd_implementation_status_screen() {
     int per = ((fanSpeed + 1) * 100) / 256;
     if (per) {
       u8g.print(itostr3(per));
-      u8g.print("%");
+      u8g.print('%');
     }
     else
   #endif
@@ -235,7 +235,7 @@ static void lcd_implementation_status_screen() {
   u8g.drawBox(0,29,128,10);
   u8g.setColorIndex(0); // white on black
   u8g.setPrintPos(2,37);
-  u8g.print("X");
+  u8g.print('X');
   u8g.drawPixel(8,33);
   u8g.drawPixel(8,35);
   u8g.setPrintPos(10,37);
@@ -247,7 +247,7 @@ static void lcd_implementation_status_screen() {
   u8g.setPrintPos(51,37);
   u8g.print(ftostr31ns(current_position[Y_AXIS]));
   u8g.setPrintPos(83,37);
-  u8g.print("Z");
+  u8g.print('Z');
   u8g.drawPixel(89,33);
   u8g.drawPixel(89,35);
   u8g.setPrintPos(91,37);