You can check your USB devices with, e.g., lsusb -t. There should also be listed which driver is in use and at which speed the devices are connected.
It seems like the driver is built into the kernel. But you can check that with the following command. When the setting is y, it is built in the kernel.
grep -i xhci /boot/config-$(uname -r)The _PLATFORM is normally not needed and is set to m, which is a loadable module.