nfp: print PCIe link bandwidth on probe

To aid debugging of performance issues caused by limited PCIe
bandwidth print the PCIe link information on probe.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>