NET: PHY: adds driver for Intel XWAY PHY

This adds support for the Intel (former Lantiq) XWAY 11G and 22E PHYs.
These PHYs are also named PEF 7061, PEF 7071, PEF 7072.

Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>