drm/msm/dpu: use encoder type to identify display type

With patch [1], DPU is broken since it continues to use
incorrect connector_type to identify the display type. Update
DPU to use the encoder type to get the info.

[1] https://patchwork.kernel.org/patch/10568269/



Acked-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

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