drm/panel: simple: Fix bus flags for Ortustech com43h4m85ulc

This display expects DE pin and data lines to be active high, add the
necessary flags.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Thierry Reding <treding@nvidia.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>