Change LCD_STR_UPLEVEL to LCD_STR_UPLEVEL[0] for consistency

Saves 4 bytes of flash and 2 bytes of SRAM (Arduino IDE 1.8.19)

Firmware/ultralcd.cpp

@@ -7269,7 +7269,7 @@ void lcd_belttest()
 			Y = eeprom_read_word((uint16_t*)(EEPROM_BELTSTATUS_Y));
 			lcd_set_cursor(10,3),lcd_printf_P(PSTR("%u"),Y);
 			lcd_set_cursor(19, 3);
-			lcd_print(LCD_STR_UPLEVEL);
+			lcd_print(LCD_STR_UPLEVEL[0]);
 			lcd_wait_for_click_delay(10);
 		}
     }