r8169: add D-Link DGE-560T identifiers.

This one includes a 8168. Not to be confused with the sky2 driven
one whose PCI vendor and device ID are the same.

Reported-by: Neyuki Inaya <in@joblog.ru>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>