drm/amdgpu: drop redundant check of harvest info

Harvest bit setting in IP data structure promises this,
so no need to set it explicitly.

Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>