iommu/amd: Extend IVRS special device data structure

This patch extends the devid_map data structure to allow
ioapic and hpet entries in ivrs to be overridden on the
kernel command line.

Reviewed-by: Shuah Khan <shuahkhan@gmail.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>