drm/ingenic: Don't request full modeset if property is not modified

Avoid requesting a full modeset if the sharpness property is not
modified, because then we don't actually need it.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220708205406.96473-5-paul@crapouillou.net