drm/amdgpu: Add pci replay count to nbio v7.9

Add implementation to get pcie replay count for nbio v7.9.

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>