iommu/vt-d: Remove unneeded validity check on dev

dev_iommu_priv_get() is being used at the top of this function which
dereferences dev. Dev cannot be NULL after this. Remove the validity
check on dev and simplify the code.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Link: https://lore.kernel.org/r/20220313150337.593650-1-usama.anjum@collabora.comSigned-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20220510023407.2759143-2-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.c

@@ -2501,7 +2501,7 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
 		}
 	}
 
-	if (dev && domain_context_mapping(domain, dev)) {
+	if (domain_context_mapping(domain, dev)) {
 		dev_err(dev, "Domain context map failed\n");
 		dmar_remove_one_dev_info(dev);
 		return NULL;