net/mlx4_core: Enable single ported IB VFs

Remove the limitation that disallows configuring single ported VFs
in the presence of IB ports, after addressing the issues that
prevented that to work.

SMI (QP0) requests/responses are still not supported for single
ported IB VFs.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>