iommu/dmar: Remove redundant ' != 0' when check return code

Usual pattern when we check for return code, which might be negative
errno, is either (ret) or (!ret).

Remove extra ' != 0' from condition.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/dmar.c

@@ -311,7 +311,7 @@ static int dmar_pci_bus_add_dev(struct dmar_pci_notify_info *info)
 				((void *)drhd) + drhd->header.length,
 				dmaru->segment,
 				dmaru->devices, dmaru->devices_cnt);
-		if (ret != 0)
+		if (ret)
 			break;
 	}
 	if (ret >= 0)