drm: atmel-hlcdc: Fix OF graph parsing

atmel_hlcdc_create_outputs() iterates over OF graph nodes and releases
the node (using of_node_put()) after each iteration, which is wrong
since for_each_endpoint_of_node() is already taking care of that.

Move the of_node_put() call in the error path.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Fixes: 17a8e03e ("drm: atmel-hlcdc: rework the output code to support drm bridges")