iommu/amd: Initialize devid variable before using it

Commit 2a0cb4e2 ("iommu/amd: Add new map for storing IVHD dev entry
type HID") added a call to DUMP_printk in init_iommu_from_acpi() which
used the value of devid before this variable was initialized.

Fixes: 2a0cb4e2 ('iommu/amd: Add new map for storing IVHD dev entry type HID')
Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>