iommu/vt-d: Remove unused iovad from dmar_domain

Not used anywhere. Cleanup it to avoid dead code.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20220527053424.3111186-1-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/iommu.h

@@ -543,7 +543,6 @@ struct dmar_domain {
 	u8 set_pte_snp:1;
 
 	struct list_head devices;	/* all devices' list */
-	struct iova_domain iovad;	/* iova's that belong to this domain */
 
 	struct dma_pte	*pgd;		/* virtual address */
 	int		gaw;		/* max guest address width */