Reduce a few magic numbers for FILENAME_LENGTH

flash: 0
RAM: 0

Firmware/Marlin_main.cpp

@@ -11313,7 +11313,7 @@ void restore_print_from_eeprom(bool mbl_was_active) {
 	int feedmultiply_rec;
 	uint8_t fan_speed_rec;
 	char cmd[48];
-	char filename[13];
+	char filename[FILENAME_LENGTH];
 	uint8_t depth = 0;
 	char dir_name[9];
 

Firmware/SdBaseFile.cpp

@@ -1015,7 +1015,7 @@ void SdBaseFile::printFatTime( uint16_t fatTime) {
  * the value zero, false, is returned for failure.
  */
 bool SdBaseFile::printName() {
-  char name[13];
+  char name[FILENAME_LENGTH];
   if (!getFilename(name)) return false;
   MYSERIAL.print(name);
   return true;

Firmware/cardreader.cpp

@@ -304,7 +304,7 @@ void CardReader::getAbsFilename(char *t)
     while(*t!=0 && cnt< MAXPATHNAMELENGTH) 
     {t++;cnt++;}  //crawl counter forward.
   }
-  if(cnt<MAXPATHNAMELENGTH-13)
+  if(cnt < MAXPATHNAMELENGTH - FILENAME_LENGTH)
     file.getFilename(t);
   else
     t[0]=0;

Firmware/cardreader.h

@@ -89,7 +89,7 @@ public:
   bool logging;
   bool sdprinting ;  
   bool cardOK ;
-  char filename[13];
+  char filename[FILENAME_LENGTH];
   // There are scenarios when simple modification time is not enough (on MS Windows)
   // Therefore these timestamps hold the most recent one of creation/modification date/times
   uint16_t crmodTime, crmodDate;