drm/amdgpu: Correct the condition of warning while bo release

Only kernel bo has kfd eviction fence.
This warning is to give a notice that kfd only remove eviction fence on
individual bos.

Tested-by: Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: xinhui pan <xinhui.pan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>