[media] media framework: rename pads init function to media_entity_pads_init()

With the MC next gen rework, what's left for media_entity_init()
is to just initialize the PADs. However, certain devices, like
a FLASH led/light doesn't have any input or output PAD.

So, there's no reason why calling media_entity_init() would be
mandatory. Also, despite its name, what this function actually
does is to initialize the PADs data. So, rename it to
media_entity_pads_init() in order to reflect that.

The media entity actual init happens during entity register,
at media_device_register_entity(). We should move init of
num_links and num_backlinks to it.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/xilinx/xilinx-tpg.c

@@ -838,7 +838,7 @@ static int xtpg_probe(struct platform_device *pdev)
 	subdev->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
 	subdev->entity.ops = &xtpg_media_ops;
 
-	ret = media_entity_init(&subdev->entity, xtpg->npads, xtpg->pads);
+	ret = media_entity_pads_init(&subdev->entity, xtpg->npads, xtpg->pads);
 	if (ret < 0)
 		goto error;