drm/msm/dsi-staging: set default topology

In case topology information is not provided in command line,
set the default topology information to no-override to avoid
accidentally selecting invalid topology.

CRs-Fixed: 2284675
Change-Id: Ie111d4b76a69c575fe6ad6f483b29564f96a6190
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>