nfp: add basic SR-IOV ndo functions

Add basic ndo_set/get_vf to support SR-IOV.

VF to egress phy static mapping by now.

Use vfcfg ABI version 2 to write the info to the FW and collect
the return value from the mailbox.

Signed-off-by: Pablo Cascón <pablo.cascon@netronome.com>
Signed-off-by: Jimmy Kizito <jimmy.kizito@netronome.com>
Signed-off-by: Rami Tomer <rami.tomer@netronome.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>