Rename sa_mac fields

Swap fields in mac_radix_entry

Remove duplicates

And enum and use switch for lookup instruction

In D35103#796527, @melifaro wrote:

what was the driver for using radix?

Move using periph lock to around softc->flags change. Add owning asserts.

In D31726#715924, @mav wrote:

While it looks OK to me, I think it would be good for different drivers to be as close as possible. And I see da got their locking slightly different in af1823cde891.