Use flash memory to emulate EEPROM (#11500)

Use a sector of the LPC flash memory to emulate EEPROM storage, removing the need to have an SD card to store system parameters.

Marlin/src/HAL/HAL_LPC1768/persistent_store_api.h

@@ -0,0 +1,24 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (C) 2016, 2017 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#include "../persistent_store_api.h"
+
+//#define FLASH_EEPROM