iommu/vt-d: Use pci_ats_supported()

The pci_ats_supported() helper checks if a device supports ATS and is
allowed to use it. By checking the ATS capability it also integrates the
pci_ats_disabled() check from pci_ats_init(). Simplify the vt-d checks.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20200520152201.3309416-5-jean-philippe@linaro.org


Signed-off-by: Joerg Roedel <jroedel@suse.de>