arm64: dts: qcom: sdm845-mtp: Add Truly display

Bring in the Truly display and enable the DSI channels to make the
mdss/gpu probe, even though we're lacking LABIB, preventing us from
seeing anything on the screen.

Tested-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Link: https://lore.kernel.org/r/20190513210747.22429-1-bjorn.andersson@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>