drm/amdgpu: no need to evict VRAM in device_fini

this VRAM evict is not needed and also cost 2seconds
to finish because the IRQ is software side disabled
before it.

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