drm/msm/dp: initialize audio_comp when audio starts

Initialize audio_comp when audio starts and wait for audio_comp at
dp_display_disable(). This will take care of both dongle unplugged
and display off (suspend) cases.

Changes in v2:
-- add dp_display_signal_audio_start()

Changes in v3:
-- restore dp_display_handle_plugged_change() at dp_hpd_unplug_handle().

Changes in v4:
-- none

Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Tested-by: Stephen Boyd <swboyd@chromium.org>
Fixes: c703d578 ("drm/msm/dp: trigger unplug event in msm_dp_display_disable")
Link: https://lore.kernel.org/r/1619048258-8717-3-git-send-email-khsieh@codeaurora.org


Signed-off-by: Rob Clark <robdclark@chromium.org>