Use only as much stack as needed for the M23 command

Marlin/cardreader.cpp

@@ -266,7 +266,7 @@ void CardReader::release() {
 }
 
 void CardReader::openAndPrintFile(const char *name) {
-  char cmd[4 + (FILENAME_LENGTH + 1) * MAX_DIR_DEPTH + 2]; // Room for "M23 ", names with slashes, a null, and one extra
+  char cmd[4 + strlen(name) + 1]; // Room for "M23 ", filename, and null
   sprintf_P(cmd, PSTR("M23 %s"), name);
   for (char *c = &cmd[4]; *c; c++) *c = tolower(*c);
   enqueue_and_echo_command_now(cmd);