Currently, DRM bridge for DPU relies on the default video
mode setting to set the encoder mode.

Add an explicit call to set the encoder mode for bridges.

Changes in v3:
- None
Reviewed-by: Archit Taneja <architt@codeauorora.org>
Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>