net: rtl8169: Support RTL-8168h/8111h

This version of the RTL-8168 is present on some development boards and
is compatible with this driver. Add support for identifying this version
of the chip so that U-Boot won't complain about it being unknown.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>