iommu/amd: Fix recently introduced compile warnings

Fix two compile warnings about unused variables introduced
by commit ecef115.

Reported-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -3499,8 +3499,6 @@ int __init amd_iommu_init_passthrough(void)
 {
 	struct iommu_dev_data *dev_data;
 	struct pci_dev *dev = NULL;
-	struct amd_iommu *iommu;
-	u16 devid;
 	int ret;
 
 	ret = alloc_passthrough_domain();