drm/amdgpu: fix amdgpu_amdkfd_remove_eviction_fence v3

Fix quite a number of bugs here. Unfortunately only compile tested.

v2: fix copy&paste error
v3: fix 80 chars issue in comment

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