net: phy: Add PHY_RTL8211E_PINE64_GIGABIT_FIX for realtek phys

Setting PHY_RTL8211E_PINE64_GIGABIT_FIX forces internal rx/tx delays off
on the PHY, as well as flipping some magical undocumented bits. The
magic number comes from the Pine64 engineering team, presumably as a
proxy from Realtek. This configuration fixes the throughput on some
Pine64 models. Packet loss of up to 60-70% has been observed without
this.

Signed-off-by: Kyle Evans <kevans@FreeBSD.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>