nfp: assign vNIC id as phys_port_name of vNICs which are not ports

When NFP is modelled as a switch we assign phys_port_name to respective
port(representor )s:

 vNIC0 - | - PF port (pf%d)     MAC/PHY (p%d[s%d]) - |E==

In most cases there is only one vNIC for communication with the switch.
If there is more than one we need to be able to identify them.  Use %d
as phys_port_name of the vNICs.

We don't have to pass ID to nfp_net_debugfs_vnic_add() separately any
more.

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>