drm/ingenic: Add ingenic_drm_bridge_atomic_enable and disable

ingenic_drm_bridge_atomic_enable allows the CRTC to be enabled after
panels have slept out, and before their display is turned on, solving
a graphical bug on the newvision nv3502c.

Also add ingenic_drm_bridge_atomic_disable to balance it out.

Signed-off-by: Christophe Branchereau <cbranchereau@gmail.com>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Artur Rojek <contact@artur-rojek.eu>
Link: https://patchwork.freedesktop.org/patch/msgid/20220321133651.291592-2-cbranchereau@gmail.com