drm/msm/dp: trigger unplug event in msm_dp_display_disable

stable inclusion
from stable-5.10.20
commit c1fe9383139a4708e137ef53e08780cc17994cd1
bugzilla: 50608

--------------------------------

[ Upstream commit c703d578 ]

1. Trigger the unplug event in msm_dp_display_disable() to shutdown audio
   properly.
2. Reset the completion before signal the disconnect event.

Fixes: 158b9aa7 ("drm/msm/dp: wait for audio notification before disabling clocks")
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Tested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Judy Hsiao <judyhsiao@chromium.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>