I still need to check if rd.driver.pre=xhci-plat-hcd is needed.
Seems so;
booting with `rd.driver.pre=xhci-plat-hcd` I get Driver=r8152, 5000M
```bash
[root@odroid-hc2-00 ~]# cat /proc/cmdline
console=ttySAC2,115200n8 cpuidle.off=1 rd.driver.pre=ledtrig-heartbeat,xhci-plat-hcd
no_bL_switcher ro root=UUID=2161061e-8612-4e18-a4e1-0e95aca6d2ff LANG=en_US.UTF-8
[root@odroid-hc2-00 ~]# lsusb -t
/: Bus 06.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
|__ Port 1: Dev 2, If 0, Class=Vendor Specific Class, Driver=r8152, 5000M
/: Bus 05.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
/: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=exynos-ohci/3p, 12M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=exynos-ehci/3p, 480M
```
dropping the option, I get Driver=r8152, 480M
```bash
[root@odroid-hc2-00 ~]# cat /proc/cmdline
console=ttySAC2,115200n8 cpuidle.off=1 rd.driver.pre=ledtrig-heartbeat no_bL_switcher ro
root=UUID=2161061e-8612-4e18-a4e1-0e95aca6d2ff LANG=en_US.UTF-8
[root@odroid-hc2-00 ~]# lsusb -t
/: Bus 06.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
/: Bus 05.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
|__ Port 1: Dev 2, If 0, Class=Vendor Specific Class, Driver=r8152, 480M
/: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 5000M
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci-hcd/1p, 480M
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=exynos-ehci/3p, 480M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=exynos-ohci/3p, 12M
```