ice: Switchdev FDB events support

Listen for SWITCHDEV_FDB_{ADD|DEL}_TO_DEVICE events while in switchdev
mode. Accept these events on both uplink and VF PR ports. Add HW
rules in newly created workqueue. FDB entries are stored in rhashtable
for lookup when removing the entry and in the list for cleanup
purpose. Direction of the HW rule depends on the type of the ports
on which the FDB event was received:

ICE_ESWITCH_BR_UPLINK_PORT:
TX rule that forwards the packet to the LAN (egress).

ICE_ESWITCH_BR_VF_REPR_PORT:
RX rule that forwards the packet to the VF associated
with the port representor.

In both cases the rule matches on the dst mac address.
All the FDB entries are stored in the bridge structure.
When the port is removed all the FDB entries associated with
this port are removed as well. This is achieved thanks to the reference
to the port that FDB entry holds.

In the fwd rule we use only one lookup type (MAC address)
but lkups_cnt variable is already introduced because
we will have more lookups in the subsequent patches.

Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>