nfp: add support for NFP5000

Add NFP5000 to supported chips, the chip is backward compatible
with NFP4000 and NFP6000, so core PCIe code needs to handle it
the same way as 4k and 6k.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>