ice: Add new VSI states to track netdev alloc/registration

Add two new VSI states, one to track if a netdev for the VSI has been
allocated and the other to track if the netdev has been registered.
Call unregister_netdev/free_netdev only when the corresponding state
bits are set.

Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>