drm/amdgpu: resume gfx userqueues

drm/amdgpu: resume gfx userqueues

This patch adds support for userqueue resume. What it typically does is
this:
- adds a new delayed work for resuming all the queues.
- schedules this delayed work from the suspend work.
- validates the BOs and replaces the eviction fence before resuming all
  the queues running under this instance of userq manager.

V2: Addressed Christian's review comments:
    - declare local variables like ret at the bottom.
    - lock all the object first, then start attaching the new fence.
    - dont replace old eviction fence, just attach new eviction fence.
    - no error logs for drm_exec_lock failures
    - no need to reserve bos after drm_exec_locked
    - schedule the resume worker immediately (not after 100 ms)
    - check for NULL BO (Arvind)

V5: Rebased wrt changes in suspend patch
    - moved amdgpu_userqueue_validate_vm_bo in this patch
    - initialized ret in resume_all

V6: Rebase
V7: Addressed review comments from Christian
    - Do not use list_for_each_safe() with vm->invalidated, its not
      correct way
V8: Fixed the race condition between suspend/close/fence

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