media: v4l2-core: Fix a potential resource leak in v4l2_fwnode_parse_link()

If fwnode_graph_get_remote_endpoint() fails, 'fwnode' is known to be NULL,
so fwnode_handle_put() is a no-op.

Release the reference taken from a previous fwnode_graph_get_port_parent()
call instead.

Also handle fwnode_graph_get_port_parent() failures.

In order to fix these issues, add an error handling path to the function
and the needed gotos.

Fixes: ca50c197 ("[media] v4l: fwnode: Support generic fwnode for parsing standardised properties")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>