drm: panel: simple: convert LG LB070WV8 fixed mode into display timings

drm: panel: simple: convert LG LB070WV8 fixed mode into display timings

At least the pixelclock has a range which can vary. Convert fixed mode
into display timings so they can be overwritten in DT if necessary.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20240110082245.417736-1-alexander.stein@ew.tq-group.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240110082245.417736-1-alexander.stein@ew.tq-group.com