The datasheet suggests 60 for tHFP, so let's adjust the number
accordingly.

This also makes the framerate be 60Hz as intended:
159916.0 * 1000 / ((1200 + 80 + 24 + 60)*(1920 + 20 + 4 + 10))
=> 60.00 Hz
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Fixes: e6d020ee ("drm/panel: support for boe, tv101wum-n53 wuxga dsi video mode panel")
Cc: Jitao Shi <jitao.shi@mediatek.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org> [added fixes tag]
Link: https://patchwork.freedesktop.org/patch/msgid/20200125050256.107404-1-drinkcat@chromium.org