[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/media-device.c

@@ -623,6 +623,8 @@ int __must_check media_device_register_entity(struct media_device *mdev,
 	WARN_ON(entity->graph_obj.mdev != NULL);
 	entity->graph_obj.mdev = mdev;
 	INIT_LIST_HEAD(&entity->links);
+	entity->num_links = 0;
+	entity->num_backlinks = 0;
 
 	spin_lock(&mdev->lock);
 	/* Initialize media_gobj embedded at the entity */