Remove iso9660 check for sbsector < 660Mb

The iso9660 filesystem code checks that the "sbsector" option is positioned within the first 660Mb of the disk.

Today the iso9660 filesystem is used on DVD's which are much bigger than 660Mb and this check prevents the sbsector option being used to specify the location of the superblock of multisession DVD's.

With this check removed I can mount the second session on a DVD-R by specifying the sbsector, even though the firmware on that drive returns bogus data for the TOC.

If an invalid large sector number is entered then a "request beyond end of device" error is reported elsewhere in the block code, but appears to do no damage.

Thanks,
Jon

@@ -447,10 +447,7 @@
        case Opt_sb:
            if (match_int(&args[0], &option))
                return 0;
-            n = option;
-            if (n > 660 * 512)
-                return 0;
-            popt->sbsector = n;
+            popt->sbsector = option;
            break;
        case Opt_check_r:
            popt->check = 'r';