media: entity: Pass entity to get_fwnode_pad operation

Add a missing pointer to the entity in the media_entity operation
get_fwnode_pad. There are no implementers of this op yet, but a future
entity that does so will almost certainly need a reference to itself
to carry out the work.

operation")

Fixes: ae45cd5e

 ("[media] media: entity: Add get_fwnode_pad entity
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>