drm/sun4i: DW HDMI: Release nodes if error happens during CRTC search

If error happens in sun8i_dw_hdmi_find_possible_crtcs(), nodes are not
released with of_node_put() before returning.

Fix that by calling of_node_put() when necessary. While on it, clean up
the code by using of_graph_get_remote_node() which also lowers number of
cases where error handling has to be performed.

Fixes: 57e23de0

 ("drm/sun4i: DW HDMI: Expand algorithm for possible crtcs")

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180710203511.18454-8-jernej.skrabec@siol.net