disp: msm: dsi: disable DSI cmd tx async wait for video mode

For video mode panels, async wait feature for DCS command
transmission may not always be reliable as additional programming
would be needed to ensure that the DCS commands are correctly scheduled.
Until this feature is properly implemented and validated, disable this
for video mode panels to avoid potential DSI command transfer
failures.

Change-Id: I18c853bc5607cc1cc523b36f6f346b213911c1a9
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>