* Digi MCA UART for ConnectCore 6UL device tree bindings

The MCA UART driver exposes an extra TTY device through the Micro Controller
Assistant. This UART can be used to wake up the system from low power modes.
Notice the MCA UART has limited capabilities compared to CPU's UARTs. Check the
documentation for a list of capabilities.

Required properties:
- compatible: must be "digi,mca-cc6ul-uart".

Optional properties:
- rts-pin: MCA IO line to be used as RTS when using hardware flow control.
- cts-pin: MCA IO line to be used as CTS when using hardware flow control.

Example:

	&mca_uart {
		compatible = "digi,mca-cc6ul-uart";
		status = "okay";
		rts-pin = <3>;
		cts-pin = <5>;
	};
