valentyusb: Add USB UART to SOC and OrangeCrab

valentyusb: Add USB UART to SOC and OrangeCrab

An extra uart is added at 0xc0008000 attached to valentyusb, using
the OrangeCrab's onboard USB port.
This has a liteuart interface, an identifier bit is added to syscon.

Generated from branch hw_cdc_eptri of
https://github.com/litex-hub/valentyusb

The generate script is based on valentyusb/sim/generate_verilog.py

UARTUSB: usbserial@8000 {
        device_type = "serial";
        compatible = "litex,liteuart";
        reg = <0x8000 0x100>;
        interrupts = <0x15 0x1>;
};

(requires extra kernel patches for early console at present v5.16)

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>