drm/meson: Fix refcount bugs in meson_vpu_has_available_connectors()

drm/meson: Fix refcount bugs in meson_vpu_has_available_connectors()

In this function, there are two refcount leak bugs:
(1) when breaking out of for_each_endpoint_of_node(), we need call
the of_node_put() for the 'ep';
(2) we should call of_node_put() for the reference returned by
of_graph_get_remote_port() when it is not used anymore.

Fixes: bbbe775ec5b5 ("drm: Add support for Amlogic Meson Graphic Controller")
Signed-off-by: Liang He <windhl@126.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220726010722.1319416-1-windhl@126.com