[media] omap3isp: remove per ISP module link creation functions

The entities to video nodes links were created on separate functions for
each ISP module but since the only thing that these functions do is to
call media_create_pad_link(), there's no need for that indirection level
and all link creation logic can be just inlined in the caller function.

Also, since the only possible failure for the link creation is a memory
allocation, there is no need for error messages since the core already
reports a very verbose message in that case.

Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>