drm/amdgpu: disable MCBP by default

stable inclusion
from stable-v6.6.7
commit c66c479480f6e90dd883cc11c692e1f3b7a95e6a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8SSQ4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c66c479480f6e90dd883cc11c692e1f3b7a95e6a



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[ Upstream commit d6a57588666301acd9d42d3b00d74240964f07f6 ]

Disable MCBP(mid command buffer preemption) by default as old Mesa
hangs with it. We shall not enable the feature that breaks old usermode
driver.

Fixes: 50a7c876 ("drm/amdgpu: enable mcbp by default on gfx9")
Signed-off-by: Jiadong Zhu <Jiadong.Zhu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>