ipq40xx: kmod-usb-dwc3-of-simple vs kmod-usb-dwc3-qcom

ipq40xx: kmod-usb-dwc3-of-simple vs kmod-usb-dwc3-qcom

Robert Marko <robimarko@gmail.com> noted in
"ipq40xx: Use kmod-usb-dwc3-qcom by default":
| Since 4.18 we cant use DWC3 OF Simple anymore so we
| have to use kmod-usb-dwc3-qcom.

This patch adds a TODO right next to the KERNEL_PATCHVER so
it will be picked up when moving to 4.19.

I would also like to point out:

All users/devs that are compiling their own images from source
and have a existing 4.14 config and want to switch to 4.19:

Please drop kmod-usb-dwc3-of-simple and add kmod-usb-dwc3-qcom
module package. Otherwise, the USB port on your router will no
longer work.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>