ata: pata_samsung_cf: simplify getting .driver_data

We should get 'driver_data' from 'struct device' directly. Going via
platform_device is an unneeded step back and forth.

Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>