AMD IOMMU: don't remove protection domain from iommu_pd_list

Impact: save unneeded logic to add and remove domains to the list

The removal of a protection domain from the iommu_pd_list is not
necessary. Another benefit is that we save complexity because we don't
have to readd it later when the device no longer uses the domain.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/kernel/amd_iommu.c

@@ -844,7 +844,6 @@ static struct dma_ops_domain *find_protection_domain(u16 devid)
 	list_for_each_entry(entry, &iommu_pd_list, list) {
 		if (entry->target_dev == devid) {
 			ret = entry;
-			list_del(&ret->list);
 			break;
 		}
 	}