iommu: Document iommu_ops.is_attach_deferred()

Add missing kerneldoc for iommu_ops.is_attach_deferred().

Fixes: e01d1913 ("iommu: Add is_attach_deferred call-back to iommu-ops")
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

include/linux/iommu.h

@@ -184,6 +184,8 @@ struct iommu_resv_region {
  * @domain_window_enable: Configure and enable a particular window for a domain
  * @domain_window_disable: Disable a particular window for a domain
  * @of_xlate: add OF master IDs to iommu grouping
+ * @is_attach_deferred: Check if domain attach should be deferred from iommu
+ *                      driver init to device driver init (default no)
  * @pgsize_bitmap: bitmap of all possible supported page sizes
  */
 struct iommu_ops {