media: xilinx-tpg: fix double put in xtpg_parse_of()

This loop was recently converted to use for_each_of_graph_port() which
automatically does __cleanup__ on the "port" iterator variable.  Delete
the calls to of_node_put(port) to avoid a double put bug.

Fixes: 393194cd ("media: xilinx-tpg: use new of_graph functions")
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>