drm/amd/display: clear optc underflow before turn off odm clock

stable inclusion
from stable-v5.10.141
commit 3c1dfeaeb3b4e3ea656041da1241e6ee3c3b3202
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I685FC

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3c1dfeaeb3b4e3ea656041da1241e6ee3c3b3202



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[ Upstream commit b2a93490 ]

[Why]
After ODM clock off, optc underflow bit will be kept there always and clear not work.
We need to clear that before clock off.

[How]
Clear that if have when clock off.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Fudong Wang <Fudong.Wang@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com>