A quick bisect indicates that the last known working kernel with 0032-USB-dwc2-add-device_reset.patch applied is 4.4.208; however, after switching drivers/usb/dwc2/. to 4.5.0, the device_reset patch will make the device un-discoverable.
Confirmed. With the patch removed, USB works fine on 18.06, 19.07 and master.
I recently acquired this little, obscure device "WS-WR512N1" (ramips) and flashed OpenWrt 19.07.3 on it. It worked well, but USB devices would not show up at all. I read a blog post from 2011 where the author of the port says that USB should work, so I tried older releases and sure enough, USB devices would appear on releases up to 17.01.x (kernel 4.4).
I bisected and the breaking commit is [[https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=fddc78bc116bc043fb5cd92dbc45cfd054c21af8|ramips: bump to v4.9]].
The dwc2 driver has seen a lot of development between kernels [[https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/log/drivers/usb/dwc2?h=v4.4.74|4.4.74]] and [[https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/log/drivers/usb/dwc2?h=v4.9.34|4.9.34]] and if 0032-USB-dwc2-add-device_reset.patch is applied on these newer kernels, the driver will be broken.