drm/panel: simple: fix BOE/HV070WSA-100 timings

Panel timings were taken from vendor code and are not fully correct -
refresh rate is about 50Hz instead of 60Hz. The patch fixes it.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180725154644.25412-9-a.hajda@samsung.com