drm/msm/hdmi: disallow interlaced

So after clarification from qcom, it seems mdp4 and mdp5 support
*de*interlacing but not generating an interlaced signal.  Which would
explain why interlaced modes never worked properly.

So disable in the one connector which was claiming to support
interlaced.

Signed-off-by: Rob Clark <robdclark@gmail.com>