ata: use pci_get_drvdata()

Use the wrapper function for getting the driver data using pci_dev
instead of using dev_get_drvdata() with &pdev->dev, so we can directly
pass a struct pci_dev.  This is a purely cosmetic change.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>