ieee802154: use ieee802154_addr instead of *_sa variants

Change all internal uses of ieee802154_addr_sa to ieee802154_addr,
except for those instances that communicate directly with userspace.

Signed-off-by: Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>