drm/amdgpu: enable eviction fence

This patch enables attachment and detachment of eviction fences.
This is just a fork of eviction fence enabling code from the first
patch of the series so that the CI testing can happen on fully
fledged code.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian Koenig <christian.koenig@amd.com>
Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
Signed-off-by: Arvind Yadav <arvind.yadav@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>