samples: usb shell: add DT overlay to support snps,dwc2 on nucleo_f413zh

Add DT overlay to be able to support and test UDC DWC2 driver
(snps,dwc2) on nucleo_f413zh board. This disables STM32 shim
driver described and configured on the SoC and board level.

Obviously,it should work with other STM32F4 boards as well and we
could have a mechanism to apply it generically using snippets.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>