drivers: usb: Fix macro USB0 undefined for certain socs

Some NXP socs use USBFS0 macro as base address for accessing the USB
registers, rather than USB0.
It generates compile-time errors, since USB0 is not defined.
Fix by defining USB0 if USB0 is not defined and USBFS0 is.

Signed-off-by: Alexandre Rey <alx.rey@icloud.com>