The 'de-active' and 'pixelclk-active' DT properties are evaluated
by of_parse_display_timing() called from of_get_drm_display_mode(),
but later lost in the conversion from videomode.flags to
drm_display_mode.flags.
Changes vs. v3:
- split the patch as suggested by Daniel Vetter
Changes vs. v2:
- removed patches which have already been applied
- created a drm_bus_flags_from_videomode() helper to prevent code
duplication as suggested by Philipp Zabel
Changes vs. v1:
- rebased on top of https://patchwork.kernel.org/patch/9113791/ as
per Philipp Zabel's request
