drm/panel: ltk050h3146w: add MIPI_DSI_MODE_VIDEO to LTK050H3148W flags

Similar to other variants, the LTK050H3148W wants to run in video mode
when displaying data. So far only the Synopsis DSI driver was using this
panel and it is always switching to video mode, independent of this flag
being set.

Other DSI drivers might handle this differently, so add the flag.

Fixes: e5f9d543 ("drm/panel: ltk050h3146w: add support for Leadtek LTK050H3148W-CTA6 variant")
Signed-off-by: Heiko Stuebner <heiko.stuebner@cherry.de>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Acked-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240320131232.327196-1-heiko@sntech.de