drm/amdgpu: add gfx eviction fence helpers

drm/amdgpu: add gfx eviction fence helpers

This patch adds basic eviction fence framework for the gfx buffers.
The idea is to:
- One eviction fence is created per gfx process, at kms_open.
- This fence is attached to all the gem buffers created
  by this process.
- This fence is detached to all the gem buffers at postclose_kms.

This framework will be further used for usermode queues.

V2: Addressed review comments from Christian
    - keep fence_ctx and fence_seq directly in fpriv
    - evcition_fence should be dynamically allocated
    - do not save eviction fence instance in BO, there could be many
      such fences attached to one BO
    - use dma_resv_replace_fence() in detach

V3: Addressed review comments from Christian
    - eviction fence create and destroy functions should be called
      only once from fpriv create/destroy
    - use dma_fence_put() in eviction_fence_destroy

V4: Addressed review comments from Christian:
    - create a separate ev_fence_mgr structure
    - cleanup fence init part
    - do not add a domain for fence owner KGD

V5: Addressed review comments from Christian:
    - drop the dma_fence_is_signaled check
    - use a local variable to access evf_mgr->ev_fence under the
      spin_lock() multiple places
    - remove the vm->is_compute_ctx check to attach gfx eviction fence,
      in gem_object_open

V6: Addressed review comments from Christian:
    - drop the return value from eviction_fence_signal
    - reserve_fence should be the first thing inside the
      attach_eviction_fence function, also keep the resv_add_fence inside
      the lock
    - remove the unwanted ev_fence check inside detach function
    - fix wrong variable check in eviction_fence_init function
    - return the error value of eviction_fence_init to the caller, dont
      keep it void.
    - fail gem_object_open if attaching of eviction_fence fails
    - detach the eviction fence only when amdgpu_vm_is_bo_always_valid
      is not true.

V7: Addressed review comments from Christian:
    - Do not add a uq_mgr ptr in ev_fence, rather add evf_mgr

V8: Move eviction fence enabling into separate patch for CI

Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@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>