Turn upper USB port into real host port

[ThomasKaiser]

According to Jared McNeill we can turn the upper USB port which is OTG normally (used in host mode -- which has performance implications and maybe stability as well) into a true host port using an own PHY by playing around with some magical bits: https://irclog.whitequark.org/linux-sunxi/2016-09-06#17478535;

Since nearly none of the average Pine64 users owns the special cable needed to use the upper OTG port in OTG mode I would think adopting this change would make sense?

(can't test, can't send PR -- no Pine64 there)