net: phylib: add link_change_notify callback to phy device

Add a notify callback to inform phy drivers when the core is about to
do its link adjustment. No change for drivers that do not implement
this callback.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/phy/phy.c
Simple merge

diff --cc include/linux/phy.h
Simple merge