ice: base subfunction aux driver

Implement subfunction driver. It is probe when subfunction port is
activated.

VSI is already created. During the probe VSI is being configured.
MAC unicast and broadcast filter is added to allow traffic to pass.

Store subfunction pointer in VSI struct. The same is done for VF
pointer. Make union of subfunction and VF pointer as only one of them
can be set with one VSI.

Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Piotr Raczynski <piotr.raczynski@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>