drivers: usb_dc_dw: add support for STM32F4 SoC family

This commit is a draft to support more controller implementations
with these drivers. The goal is also to make it easier to port
this driver to the new UDC API later.
We use compatible, like st,stm24f4-fsotg to support and enable
vendor-specific quirk. The core of the driver remains generic,
and therefore described and enabled by snps,dwc2 compatible.

STM32F4 support requires PINCTRL, even though pinctrl API is
generic, not all platforms implement it, so we have to include
and compile it conditionally.

Now we also switch to use new snps,dwc2 compatible and
explicitly force the controller into device mode,
as we do not support other roles or role changes.

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