drm/amdgpu: Hide xcp partition sysfs under SRIOV

XCP partitions should not be visible for the VF for GFXIP 9.4.3.

Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>