drm/amdgpu: Remove redundant logic in GC v9.4.3

GFXOFF check is not needed for GC v9.4.3. Also, save/restore list is
available by default.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>