iommu/amd: Fix checking of pci dma aliases

Commit 61289cba ('iommu/amd: Remove old alias handling code')
removed the old alias handling code from the AMD IOMMU
driver because this is now handled by the IOMMU core code.

But this also removed the handling of PCI aliases, which is
not handled by the core code. This caused issues with PCI
devices that have hidden PCIe-to-PCI bridges that rewrite
the request-id.

Fix this bug by re-introducing some of the removed functions
from commit 61289cba and add a alias field
'struct iommu_dev_data'. This field carrys the return value
of the get_alias() function and uses that instead of the
amd_iommu_alias_table[] array in the code.

Fixes: 61289cba ('iommu/amd: Remove old alias handling code')
Cc: stable@vger.kernel.org # v4.4+
Tested-by: Tomasz Golinski <tomaszg@math.uwb.edu.pl>
Signed-off-by: Joerg Roedel <jroedel@suse.de>