fpga: fpga-region: fix kernel-doc formatting issues

To fix below kernel-doc warnings this patch does the following
->Replaced Return\Returns with 'Return:' keyword.
->Added 'Return' description For __init of_fpga_region_init()' API.
->Added description for 'child_regions_with_firmware()' API.

warning: No description found for return value of
'of_fpga_region_find'.
warning: No description found for return value of
'of_fpga_region_get_bridges'.
warning: missing initial short description on line:
* child_regions_with_firmware
warning: No description found for return value of
'child_regions_with_firmware'.
warning: No description found for return value of
'of_fpga_region_notify_pre_apply'.
warning: No description found for return value of
'of_fpga_region_notify'.
warning: No description found for return value of
'of_fpga_region_init'.

Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
Link: https://lore.kernel.org/r/20220423170235.2115479-6-nava.manne@xilinx.com
Signed-off-by: Xu Yilun <yilun.xu@intel.com>

drivers/fpga/of-fpga-region.c

@@ -28,7 +28,7 @@ MODULE_DEVICE_TABLE(of, fpga_region_of_match);
  *
  * Caller will need to put_device(&region->dev) when done.
  *
- * Returns FPGA Region struct or NULL
+ * Return: FPGA Region struct or NULL
  */
 static struct fpga_region *of_fpga_region_find(struct device_node *np)
 {
@@ -80,7 +80,7 @@ static struct fpga_manager *of_fpga_region_get_mgr(struct device_node *np)
  * Caller should call fpga_bridges_put(&region->bridge_list) when
  * done with the bridges.
  *
- * Return 0 for success (even if there are no bridges specified)
+ * Return: 0 for success (even if there are no bridges specified)
  * or -EBUSY if any of the bridges are in use.
  */
 static int of_fpga_region_get_bridges(struct fpga_region *region)
@@ -139,13 +139,13 @@ static int of_fpga_region_get_bridges(struct fpga_region *region)
 }
 
 /**
- * child_regions_with_firmware
+ * child_regions_with_firmware - Used to check the child region info.
  * @overlay: device node of the overlay
  *
  * If the overlay adds child FPGA regions, they are not allowed to have
  * firmware-name property.
  *
- * Return 0 for OK or -EINVAL if child FPGA region adds firmware-name.
+ * Return: 0 for OK or -EINVAL if child FPGA region adds firmware-name.
  */
 static int child_regions_with_firmware(struct device_node *overlay)
 {
@@ -184,7 +184,7 @@ static int child_regions_with_firmware(struct device_node *overlay)
  * Given an overlay applied to an FPGA region, parse the FPGA image specific
  * info in the overlay and do some checking.
  *
- * Returns:
+ * Return:
  *   NULL if overlay doesn't direct us to program the FPGA.
  *   fpga_image_info struct if there is an image to program.
  *   error code for invalid overlay.
@@ -279,7 +279,7 @@ ret_no_info:
  * If the checks fail, overlay is rejected and does not get added to the
  * live tree.
  *
- * Returns 0 for success or negative error code for failure.
+ * Return: 0 for success or negative error code for failure.
  */
 static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
 					   struct of_overlay_notify_data *nd)
@@ -339,7 +339,7 @@ static void of_fpga_region_notify_post_remove(struct fpga_region *region,
  * This notifier handles programming an FPGA when a "firmware-name" property is
  * added to an fpga-region.
  *
- * Returns NOTIFY_OK or error if FPGA programming fails.
+ * Return: NOTIFY_OK or error if FPGA programming fails.
  */
 static int of_fpga_region_notify(struct notifier_block *nb,
 				 unsigned long action, void *arg)
@@ -446,6 +446,8 @@ static struct platform_driver of_fpga_region_driver = {
 /**
  * of_fpga_region_init - init function for fpga_region class
  * Creates the fpga_region class and registers a reconfig notifier.
+ *
+ * Return: 0 on success, negative error code otherwise.
  */
 static int __init of_fpga_region_init(void)
 {