Fix broken EEPROM save/load

Marlin/configuration_store.cpp

     if (!eeprom_error) {
       const int eeprom_size = eeprom_index;
 
+      const uint16_t tcrc = working_crc;
+
       // Write the EEPROM header
       eeprom_index = EEPROM_OFFSET;
+
       EEPROM_WRITE(version);
-      EEPROM_WRITE(working_crc);
+      EEPROM_WRITE(tcrc);
 
       // Report storage size
       SERIAL_ECHO_START;
       SERIAL_ECHOPAIR("Settings Stored (", eeprom_size - (EEPROM_OFFSET));
-      SERIAL_ECHOPAIR(" bytes; crc ", working_crc);
+      SERIAL_ECHOPAIR(" bytes; crc ", tcrc);
       SERIAL_ECHOLNPGM(")");
     }
 
       }
       else {
         SERIAL_ERROR_START;
-        SERIAL_ERRORPGM("EEPROM checksum mismatch - (stored CRC)");
+        SERIAL_ERRORPGM("EEPROM CRC mismatch - (stored) ");
         SERIAL_ERROR(stored_crc);
         SERIAL_ERRORPGM(" != ");
         SERIAL_ERROR(working_crc);
-        SERIAL_ERRORLNPGM(" (calculated CRC)!");
+        SERIAL_ERRORLNPGM(" (calculated)!");
         reset();
       }
 
     return !eeprom_error;
   }
 
-
   #if ENABLED(AUTO_BED_LEVELING_UBL)
 
     void ubl_invalid_slot(const int s) {
         if (!WITHIN(slot, 0, a - 1)) {
           ubl_invalid_slot(a);
           SERIAL_PROTOCOLPAIR("E2END=", E2END);
-          SERIAL_PROTOCOLPAIR(" meshes_end=", (int)meshes_end);
+          SERIAL_PROTOCOLPAIR(" meshes_end=", meshes_end);
           SERIAL_PROTOCOLLNPAIR(" slot=", slot);
           SERIAL_EOL;
           return;

Marlin/configuration_store.h

       #if ENABLED(AUTO_BED_LEVELING_UBL) // Eventually make these available if any leveling system
                                          // That can store is enabled
         static int meshes_begin;
-        const static int mat_end = E2END;            // Mesh allocation table; this may not end up being necessary
-        const static int meshes_end = mat_end - 128; // 128 is a placeholder for the size of the MAT
+        const static int meshes_end = E2END - 128; // 128 is a placeholder for the size of the MAT; the MAT will always
+                                                   // live at the very end of the eeprom
 
       #endif
 

Marlin/utility.cpp

 #if ENABLED(EEPROM_SETTINGS)
 
   void crc16(uint16_t *crc, const void * const data, uint16_t cnt) {
-    uint8_t *ptr = (uint8_t*)data;
-    while (cnt-- > 0) {
+    uint8_t *ptr = (uint8_t *)data;
+    while (cnt--) {
       *crc = (uint16_t)(*crc ^ (uint16_t)(((uint16_t)*ptr++) << 8));
       for (uint8_t x = 0; x < 8; x++)
         *crc = (uint16_t)((*crc & 0x8000) ? ((uint16_t)(*crc << 1) ^ 0x1021) : (*crc << 1));