drm/panel: simple: fix AUO g185han01 horizontal blanking

The horizontal blanking periods are too short, as the values are
specified for a single LVDS channel. Since this panel is dual LVDS
they need to be doubled. With this change the panel reaches its
nominal vrefresh rate of 60Fps, instead of the 64Fps with the
current wrong blanking.

Philipp Zabel added:
The datasheet specifies 960 active clocks + 40/128/160 clocks blanking
on each of the two LVDS channels (min/typical/max), so doubled this is
now correct.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1562764060.23869.12.camel@pengutronix.de