dt/misc: add bindings documentation for ifm camera sensor interface

IFM camera sensor interface on mpc5200 LocalPlus bus

Required properties:

- compatible: "ifm,o2d-csi"

- reg: specifies sensor chip select number and associated address range

- interrupts: external interrupt line number and interrupt sense mode

  of the interrupt line signaling frame valid events

- gpios: three gpio-specifiers for "capture", "reset" and "master enable"

  GPIOs (strictly in this order).

- ifm,csi-clk-handle: the phandle to a node in the DT describing the sensor

  clock generator. This node is usually a general purpose timer controller.

- ifm,csi-addr-bus-width: address bus width (valid values are 16, 24, 25)

- ifm,csi-data-bus-width: data bus width (valid values are 8 and 16)

- ifm,csi-wait-cycles: sensor bus wait cycles

Optional properties:

- ifm,csi-byte-swap: if this property is present, the byte swapping on

  the bus will be enabled.

Example:

	csi@3,0 {

		compatible = "ifm,o2d-csi";

		reg = <3 0 0x00100000>;		/* CS 3, 1 MiB range */

		interrupts = <1 1 2>;		/* IRQ1, edge falling */

		ifm,csi-clk-handle = <&timer7>;

		gpios = <&gpio_simple 23 0	/* image_capture */

			 &gpio_simple 26 0	/* image_reset */

			 &gpio_simple 29 0>;	/* image_master_en */

		ifm,csi-addr-bus-width = <24>;

		ifm,csi-data-bus-width = <8>;

		ifm,csi-wait-cycles = <0>;

	};

The base address of the used chip select is specified in the

ranges property of the parent localbus node, for example:

	ranges = <0 0 0xff000000 0x01000000

		  3 0 0xe3000000 0x00100000>;