pinctrl: Document pinctrl-single,pins when #pinctrl-cells = 2

specified in the pinctrl-bindings.txt document in this directory.

The pin configuration nodes for pinctrl-single are specified as pinctrl

register offset and value pairs using pinctrl-single,pins. Only the bits

specified in pinctrl-single,function-mask are updated. For example, setting

a pin for a device could be done with:

register offset and values using pinctrl-single,pins. Only the bits specified

in pinctrl-single,function-mask are updated.

When #pinctrl-cells = 1, then setting a pin for a device could be done with:

	pinctrl-single,pins = <0xdc 0x118>;

Where 0xdc is the offset from the pinctrl register base address for the

device pinctrl register, and 0x118 contains the desired value of the

pinctrl register. See the device example and static board pins example

below for more information.

Where 0xdc is the offset from the pinctrl register base address for the device

pinctrl register, and 0x118 contains the desired value of the pinctrl register.

When #pinctrl-cells = 2, then setting a pin for a device could be done with:

	pinctrl-single,pins = <0xdc 0x30 0x07>;

Where 0x30 is the pin configuration value and 0x07 is the pin mux mode value.

These two values are OR'd together to produce the value stored at offset 0xdc.

See the device example and static board pins example below for more information.

In case when one register changes more than one pin's mux the

pinctrl-single,bits need to be used which takes three parameters: