Allow creation of netdevsim ports for VFs along with allocations of
corresponding net devices and devlink ports.
Add enums and helpers to distinguish PFs' ports from VFs' ports.

Ports creation/deletion debugfs API intended to be used with physical
ports only.
VFs instantiation will be done in one of the next patches.
Signed-off-by: NDmytro Linkin <dlinkin@nvidia.com>
Reviewed-by: NJiri Pirko <jiri@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>