drm/amdgpu: Skip pcie_replay_count sysfs creation for VF

VFs cannot read the NAK_COUNTER register. This information is only
available through PMFW metrics.

Signed-off-by: Victor Skvortsov <victor.skvortsov@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>