drm/amdgpu: Skip access gfx11 golden registers under SRIOV

[Why]
Golden registers are PF-only registers on gfx11.
RLCG interface will return "out-of-range" under SRIOV VF.

[How]
Skip access gfx11 golden registers under SRIOV.

Reviewed-by: Horace Chen <horace.chen@amd.com>
Signed-off-by: ZhenGuo Yin <zhenguo.yin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>