ACPI/IORT: Add missing comment for iort_dev_find_its_id()

Add missing req_id parameter to the iort_dev_find_its_id() function
kernel-doc comment.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Ming Lei <ming.lei@canonical.com>
Tested-by: Wei Xu <xuwei5@hisilicon.com>
Tested-by: Sinan Kaya <okaya@codeaurora.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Tomasz Nowicki <tn@semihalf.com>

drivers/acpi/arm64/iort.c

@@ -450,6 +450,7 @@ u32 iort_msi_map_rid(struct device *dev, u32 req_id)
 /**
  * iort_dev_find_its_id() - Find the ITS identifier for a device
  * @dev: The device.
+ * @req_id: Device's requester ID
  * @idx: Index of the ITS identifier list.
  * @its_id: ITS identifier.
  *