drm/amdgpu: Fix potential fence use-after-free v2

mainline inclusion
from mainline-v6.5-rc1
commit 2e54154b
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I8YD58
CVE: CVE-2023-51042

Reference: https://github.com/torvalds/linux/commit/2e54154b9f27262efd0cb4f903cc7d5ad1fe9628



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fence Decrements the reference count before exiting.
Avoid Race Vulnerabilities for fence use-after-free.

v2 (chk): actually fix the use after free and not just move it.

Signed-off-by: shanzhulig <shanzhulig@gmail.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: GUO Zihua <guozihua@huawei.com>