pktcdvd: use sysfs_emit() to instead of scnprintf()

pktcdvd: use sysfs_emit() to instead of scnprintf()

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230310164549.22133-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>