ice: enable LLDP TX for VFs through tc

ice: enable LLDP TX for VFs through tc

Only a single VSI can be in charge of sending LLDP frames, sometimes it is
beneficial to assign this function to a VF, that is possible to do with tc
capabilities in the switchdev mode. It requires first blocking the PF from
sending the LLDP frames with a following command:

tc filter add dev <ifname> egress protocol lldp flower skip_sw action drop

Then it becomes possible to configure a forward rule from a VF port
representor to uplink instead.

tc filter add dev <vf_ifname> ingress protocol lldp flower skip_sw
action mirred egress redirect dev <ifname>

How LLDP exclusivity was done previously is LLDP traffic was blocked for a
whole port by a single rule and PF was bypassing that. Now at least in the
switchdev mode, every separate VSI has to have its own drop rule. Another
complication is the fact that tc does not respect when the driver refuses
to delete a rule, so returning an error results in a HW rule still present
with no way to reference it through tc. This is addressed by allowing the
PF rule to be deleted at any time, but making the VF forward rule "dormant"
in such case, this means it is deleted from HW but stays in tc and driver's
bookkeeping to be restored when drop rule is added back to the PF.

Implement tc configuration handling which enables the user to transmit LLDP
packets from VF instead of PF.

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>