lantiq: add phy led config support over devicetree bindings

lantiq: add phy led config support over devicetree bindings

This patch adds the posibility to config the led behaviour of the lantiq phys
over the devicetree bindings.It patches the 0023-NET-PHY-adds-driver-for-lantiq-PHY11G
for 3.18 and 4.1. I have also added a register description overview for
applicable values. This goes to the documentation folder in the linux kernel.

Signed-off-by: Florian Eckert <Eckert.Florian@googlemail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@47566 3c298f89-4303-0410-b956-a3cf2f4a3e73