lan78xx: Remove phy defines in lan78xx.h and use defines in include/linux/microchipphy.h

Remove phy defines in lan78xx.h and use defines in include/linux/microchipphy.h.

Signed-off-by: Woojung Huh <woojung.huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>