Fix a bug when booting HDM17x64_17.20.0_ADV_Linux_Downloadly.ir.iso

INSTALL/grub/grub.cfg

@@ -1017,14 +1017,13 @@ function legacy_linux_menu_func {
             loopback loop "$1$2"
         fi
 
-        if [ -f (loop)/isolinux/isolinux.cfg ]; then
-            if vt_iso9660_isjoliet; then
-                vt_iso9660_nojoliet 1
-                loopback -d loop
-                loopback loop "$1$2"
-            fi
+        
+        if vt_syslinux_need_nojoliet "$1$2"; then
+            vt_iso9660_nojoliet 1
+            loopback -d loop
+            loopback loop "$1$2"
         fi
-    
+
         vt_load_cpio  $vtoy_path  "$2" "$1" "busybox=$ventoy_busybox_ver"
 
         vt_linux_clear_initrd