drm/msm/dpu: enable DPU_MDP_AUDIO_SELECT for sc8180x

drm/msm/dpu: enable DPU_MDP_AUDIO_SELECT for sc8180x

According to the discussion ([1]) on the mailing list, platforms before
sm8250 (and derivatives) should program HDMI_DP_CORE_SELECT register to
route audio to the DP ports. Enable DPU_MDP_AUDIO_SELECT on sc8180x to
program correponding register.

[1] https://lore.kernel.org/all/f86504ba-835a-6e30-6c30-8bb89b1359c4@quicinc.com/

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/518461/
Link: https://lore.kernel.org/r/20230115140022.489881-1-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>