drm/amdgpu: Replace ttm_bo_wait with amdgpu_bo_sync_wait

The fence_owner logic in amdgpu_sync_wait will allow waiting without
having to temporarily remove eviction fences.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>