drm/amdgpu: flush coredump work before HW teardown

drm/amdgpu: flush coredump work before HW teardown

In amdgpu_device_fini_hw(), deferred coredump formatting work may still
be pending when hardware and IP components are being torn down. Since
the work may access device registers and memory that will be freed or
powered off, it must be completed before proceeding.

Add a flush_work() call for adev->coredump_work, guarded by
CONFIG_DEV_COREDUMP, to ensure any pending coredump work finishes
before the device enters the early IP fini stage.

This avoids potential use-after-free or accessing hardware resources
that are no longer available.

Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Suggested-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Jesse Zhang <jesse.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>