Followup to SD menu optimization (#15252)

Marlin/src/lcd/menu/menu_media.cpp

 
   #if HAS_GRAPHICAL_LCD
     static uint16_t fileCnt;
+    static bool at_root;
     if (ui.first_page) {
       fileCnt = card.get_num_Files();
       card.getWorkDirName();
+      at_root = card.filename[0] == '/';
     }
   #else
     const uint16_t fileCnt = card.get_num_Files();
     card.getWorkDirName();
+    const bool at_root = card.filename[0] == '/';
   #endif
 
   START_MENU();
   MENU_BACK(MSG_MAIN);
-  if (card.filename[0] == '/') {
+  if (at_root) {
     #if !PIN_EXISTS(SD_DETECT)
       MENU_ITEM(function, LCD_STR_REFRESH MSG_REFRESH, lcd_sd_refresh);
     #endif

Marlin/src/sd/SdBaseFile.cpp

  *
  * \return true for success, false for failure.
  */
-bool SdBaseFile::getFilename(char * const name) {
+bool SdBaseFile::getDosName(char * const name) {
   if (!isOpen()) return false;
 
   if (isRoot()) {
  */
 bool SdBaseFile::printName() {
   char name[FILENAME_LENGTH];
-  if (!getFilename(name)) return false;
+  if (!getDosName(name)) return false;
   SERIAL_ECHO(name);
   return true;
 }

Marlin/src/sd/SdBaseFile.h

    */
   bool isRoot() const { return type_ == FAT_FILE_TYPE_ROOT_FIXED || type_ == FAT_FILE_TYPE_ROOT32; }
 
-  bool getFilename(char * const name);
+  bool getDosName(char * const name);
   void ls(uint8_t flags = 0, uint8_t indent = 0);
 
   bool mkdir(SdBaseFile* dir, const char* path, bool pFlag = true);

Marlin/src/sd/cardreader.cpp

 void CardReader::printFilename() {
   if (file.isOpen()) {
     char dosFilename[FILENAME_LENGTH];
-    file.getFilename(dosFilename);
+    file.getDosName(dosFilename);
     SERIAL_ECHO(dosFilename);
     #if ENABLED(LONG_FILENAME_HOST_SUPPORT)
       getfilename(0, dosFilename);
 }
 
 void appendAtom(SdFile &file, char *& dst, uint8_t &cnt) {
-  file.getFilename(dst);
+  file.getDosName(dst);
   while (*dst && cnt < MAXPATHNAMELENGTH) { dst++; cnt++; }
   if (cnt < MAXPATHNAMELENGTH) { *dst = '/'; dst++; cnt++; }
 }

Marlin/src/sd/cardreader.h

   static inline void setIndex(const uint32_t index) { sdpos = index; file.seekSet(index); }
   static inline uint32_t getIndex() { return sdpos; }
   static inline uint8_t percentDone() { return (isFileOpen() && filesize) ? sdpos / ((filesize + 99) / 100) : 0; }
-  static inline char* getWorkDirName() { workDir.getFilename(filename); return filename; }
+  static inline char* getWorkDirName() { workDir.getDosName(filename); return filename; }
   static inline int16_t read(void* buf, uint16_t nbyte) { return file.isOpen() ? file.read(buf, nbyte) : -1; }
   static inline int16_t write(void* buf, uint16_t nbyte) { return file.isOpen() ? file.write(buf, nbyte) : -1; }