face: use NetworkInterfaceInfo directly in EthernetFace.

Finally getting rid of EthernetFactory::findAllInterfaces()
and EthernetFace::getInterfaceAddress().

Change-Id: I94fe2016cc98778af3115569b1d21d5c48425d9c
face: mark UnixStreamFace constructor explicit.

The keyword was accidentally removed in commit
355c066fe188ca0a1b51a43a39f4e9ef402d1448.

Change-Id: I1e345cf5ccb1d5ddc56419fb19493eb446590880
face: delete redundant protocol typedefs.

Change-Id: I32e1100e7395070a29ee813658aac82b63b6c4f2