STMicroelectonics Multi-Function eXpander (STMFX) Core bindings

ST Multi-Function eXpander (STMFX) is a slave controller using I2C for
communication with the main MCU. Its main features are GPIO expansion, main
MCU IDD measurement (IDD is the amount of current that flows through VDD) and
resistive touchscreen controller.

Required properties:
- compatible: should be "st,stmfx-0300".
- reg: I2C slave address of the device.
- interrupts: interrupt specifier triggered by MFX_IRQ_OUT signal.
  Please refer to ../interrupt-controller/interrupt.txt

Optional properties:
- drive-open-drain: configure MFX_IRQ_OUT as open drain.
- vdd-supply: phandle of the regulator supplying STMFX.

Example:

	stmfx: stmfx@42 {
		compatible = "st,stmfx-0300";
		reg = <0x42>;
		interrupts = <8 IRQ_TYPE_EDGE_RISING>;
		interrupt-parent = <&gpioi>;
		vdd-supply = <&v3v3>;
	};

Please refer to ../pinctrl/pinctrl-stmfx.txt for STMFX GPIO expander function bindings.
