ice: process events created by lag netdev event handler

Add in the function framework for the processing of LAG events.  Also add
in helper function to perform common tasks.

Add the basis of the process of linking a lower netdev to an upper netdev.

Reviewed-by: Daniel Machon <daniel.machon@microchip.com>
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Tested-by: Sujai Buvaneswaran <sujai.buvaneswaran@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>