* NXP SC16IS7xx advanced Universal Asynchronous Receiver-Transmitter (UART)

Required properties:
- compatible: Should be one of the following:
  - "nxp,sc16is740" for NXP SC16IS740,
  - "nxp,sc16is741" for NXP SC16IS741,
  - "nxp,sc16is750" for NXP SC16IS750,
  - "nxp,sc16is752" for NXP SC16IS752,
  - "nxp,sc16is760" for NXP SC16IS760,
  - "nxp,sc16is762" for NXP SC16IS762.
- reg: I2C address of the SC16IS7xx device.
- interrupt-parent: The phandle for the interrupt controller that
  services interrupts for this IC.
- interrupts: Should contain the UART interrupt
- clocks: Reference to the IC source clock.

Optional properties:
- gpio-controller: Marks the device node as a GPIO controller.
- #gpio-cells: Should be two. The first cell is the GPIO number and
  the second cell is used to specify the GPIO polarity:
    0 = active high,
    1 = active low.

Example:
        sc16is750: sc16is750@51 {
                compatible = "nxp,sc16is750";
                reg = <0x51>;
                clocks = <&clk20m>;
                interrupt-parent = <&gpio3>;
                interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
                gpio-controller;
                #gpio-cells = <2>;
        };