r8169: remove manual autoneg restart workaround

According to Neil who reported the issue leading to this
workaround, the workaround is no longer needed since
version 5.0. So let's remove it.

This was the bug report leading to the workaround:
https://bugzilla.kernel.org/show_bug.cgi?id=201081



Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Neil MacLeod <neil@nmacleod.com>
Signed-off-by: David S. Miller <davem@davemloft.net>