drivers/block/sx8.c: use module_pci_driver()

Use module_pci_driver() macro which makes the code smaller and simpler.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>