media: stm32-dcmi: use int type to store negative error codes

Change "ret" from unsigned int to int type in dcmi_framesizes_init()
and dcmi_graph_notify_bound() to store negative error codes or zero
returned by v4l2_subdev_call() and media_create_pad_link() - this
better aligns with the coding standards and maintains code consistency.

No effect on runtime.

Signed-off-by: Qianfeng Rong <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/platform/st/stm32/stm32-dcmi.c

···
 		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
 		.code = dcmi->sd_format->mbus_code,
 	};
-	unsigned int ret;
 	unsigned int i;
+	int ret;
 
 	/* Allocate discrete framesizes array */
 	while (!v4l2_subdev_call(subdev, pad, enum_frame_size,
···
 				   struct v4l2_async_connection *asd)
 {
 	struct stm32_dcmi *dcmi = notifier_to_dcmi(notifier);
-	unsigned int ret;
 	int src_pad;
+	int ret;
 
 	dev_dbg(dcmi->dev, "Subdev \"%s\" bound\n", subdev->name);