iommu: Document iommu_ops.iotlb_sync_map()

Add missing kerneldoc for iommu_ops.iotlb_sync_map().

Fixes: 1d7ae53b ("iommu: Introduce iotlb_sync_map callback")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

include/linux/iommu.h

@@ -169,6 +169,7 @@ struct iommu_resv_region {
  * @unmap: unmap a physically contiguous memory region from an iommu domain
  * @flush_iotlb_all: Synchronously flush all hardware TLBs for this domain
  * @iotlb_range_add: Add a given iova range to the flush queue for this domain
+ * @iotlb_sync_map: Sync mappings created recently using @map to the hardware
  * @iotlb_sync: Flush all queued ranges from the hardware TLBs and empty flush
  *            queue
  * @iova_to_phys: translate iova to physical address