drm/msm/dpu: add HDMI output support

MSM8998 and the older Qualcomm platforms support HDMI outputs. Now as
DPU encoder is ready, add support for using INTF_HDMI.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Arnaud Vrac <rawoul@gmail.com>
Tested-by: Arnaud Vrac <rawoul@gmail.com> # on msm8998
Patchwork: https://patchwork.freedesktop.org/patch/532371/
Link: https://lore.kernel.org/r/20230415171926.85774-3-dmitry.baryshkov@linaro.org


Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>