x86, AMD IOMMU: replace UPDATE_LAST_BDF macro with a function

This patch replaces the UPDATE_LAST_BDF macro in the init code with the
update_last_devid function.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>