[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/omap3isp/isppreview.c

@@ -2287,7 +2287,7 @@ static int preview_init_entities(struct isp_prev_device *prev)
 	pads[PREV_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
 
 	me->ops = &preview_media_ops;
-	ret = media_entity_init(me, PREV_PADS_NUM, pads);
+	ret = media_entity_pads_init(me, PREV_PADS_NUM, pads);
 	if (ret < 0)
 		return ret;