r8169: tweak max read request size for newer chips also in jumbo mtu mode

So far we don't increase the max read request size if we switch to
jumbo mode before bringing up the interface for the first time.
Let's change this.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>