Device-Tree bindings for UART slave devices

A node describing a slave device defines a phandle to reference the UART
the device is connected to. In the (unexpected) case of two or more UARTs
a list of phandles can be specified.

properties:
	- uart: (list of) phandle(s) of UART(s) the device is connected to


example:

	gps {
		compatible = "wi2wi,w2sg0004";
		uart = <&uart1>;
	};
