iommu/amd: Use pci_prg_resp_pasid_required()

Commit e5567f5f ("PCI/ATS: Add pci_prg_resp_pasid_required()
interface.") added a common interface to check the PASID bit in the PRI
capability. Use it in the AMD driver.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>