drm/panel: nt39016: Add support for multiple modes

Add support for multiple drm_display_mode entries. This will allow to
add a 50 Hz mode later.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20200408095830.8131-1-paul@crapouillou.net


Acked-by: Sam Ravnborg <sam@ravnborg.org>