STMicroelectronics STIH4xx HDMI CEC driver

Required properties:
 - compatible : value should be "st,stih-cec"
 - reg : Physical base address of the IP registers and length of memory
	 mapped region.
 - clocks : from common clock binding: handle to HDMI CEC clock
 - interrupts : HDMI CEC interrupt number to the CPU.
 - pinctrl-names: Contains only one value - "default"
 - pinctrl-0: Specifies the pin control groups used for CEC hardware.
 - resets: Reference to a reset controller
 - hdmi-phandle: Phandle to the HDMI controller, see also cec.txt.

Example for STIH407:

sti-cec@94a087c {
	compatible = "st,stih-cec";
	reg = <0x94a087c 0x64>;
	clocks = <&clk_sysin>;
	clock-names = "cec-clk";
	interrupts = <GIC_SPI 140 IRQ_TYPE_NONE>;
	interrupt-names = "cec-irq";
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_cec0_default>;
	resets = <&softreset STIH407_LPM_SOFTRESET>;
	hdmi-phandle = <&hdmi>;
};