drm/meson: encoder_hdmi: Fix refcount leak in meson_encoder_hdmi_init

of_graph_get_remote_node() returns remote device nodepointer with
refcount incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: e67f6037 ("drm/meson: split out encoder from meson_dw_hdmi")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220601033927.47814-3-linmq006@gmail.com