Intel x86 PINCTRL/GPIO controller

Pin-muxing on x86 can be described with a node for the PINCTRL master
node and a set of child nodes for each pin on the SoC.

The PINCTRL master node requires the following properties:
- compatible : "intel,x86-pinctrl"

Pin nodes must be children of the pinctrl master node and can
contain the following properties:
- pad-offset	- (required) offset in the IOBASE for the pin to configure
- gpio-offset	- (required only when 'mode-gpio' is set) 2 cells
			- offset in the GPIOBASE for the pin to configure
			- the bit shift in this register (4 = bit 4)
- mode-gpio	- (optional) standalone property to force the pin into GPIO mode
- mode-func	- (optional) function number to assign to the pin. If
			'mode-gpio' is set, this property will be ignored.
in case of 'mode-gpio' property set:
- output-value	- (optional) this set the default output value of the GPIO
- direction	- (optional) this set the direction of the gpio
- pull-strength	- (optional) this set the pull strength of the pin
- pull-assign	- (optional) this set the pull assignement (up/down) of the pin
- invert	- (optional) this input pin is inverted

Example:

pin_usb_host_en0@0 {
	gpio-offset = <0x80 8>;
	pad-offset = <0x260>;
	mode-gpio;
	output-value = <1>;
	direction = <PIN_OUTPUT>;
};
