pktcdvd: replace sscanf() by kstrtoul()

The checkpatch.pl warns: "Prefer kstrto<type> to single variable sscanf".
Fix the code accordingly.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230310164549.22133-3-andriy.shevchenko@linux.intel.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>