drm/ingenic: ipu: Only restart manually on older SoCs

On older SoCs, it is necessary to restart manually the IPU when a frame
is done processing. Doing so on newer SoCs (JZ4760/70) kinds of work
too, until the input or output resolutions or the framerate are too
high.

Make it work properly on newer SoCs by letting the LCD controller
trigger the IPU frame restart signal.

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200730144830.10479-2-paul@crapouillou.net