pktcdvd: Use put_unaligned_be16() and get_unaligned_be16()

This makes the driver code slightly better to understand.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230310164549.22133-8-andriy.shevchenko@linux.intel.com


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