Fix setInterfaceEnabled method signature

- Mark setInterfaceEnabled as public as it is called from
  EthernetServiceImpl.
- Mark EthernetCallback as NonNull.
- Remove final qualifiers as they have no meaning to the caller and make
  the code harder to read (by introducing line breaks).

Test: TH
Change-Id: I9f030e8c40938e5f1e9ad0a32313828eeea4fdd3
1 file changed