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

This version of the RTL-8168 chip can be found on some add-in cards sold
by CSL-Computer GmbH & Co. KG. The chip isn't special in any way, but it
needs to have the ChipCmd register programmed after the DMA descriptors
have been set up, so make sure that happens by adding an entry to the
chip information table.

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