spi: bcm2835aux: spi: add bindings for the bcm2835 auxiliary spi devices

Broadcom BCM2835 auxiliar SPI1/2 controller

The BCM2835 contains two forms of SPI master controller, one known simply as

SPI0, and the other known as the "Universal SPI Master"; part of the

auxiliary block. This binding applies to the SPI1/2 controller.

Required properties:

- compatible: Should be "brcm,bcm2835-aux-spi".

- reg: Should contain register location and length for the spi block

- interrupts: Should contain shared interrupt of the aux block

- clocks: The clock feeding the SPI controller - needs to

	  point to the auxiliar clock driver of the bcm2835,

	  as this clock will enable the output gate for the specific

	  clock.

- cs-gpios: the cs-gpios (native cs is NOT supported)

	    see also spi-bus.txt

Example:

spi1@7e215080 {

	compatible = "brcm,bcm2835-aux-spi";

	reg = <0x7e215080 0x40>;

	interrupts = <1 29>;

	clocks = <&aux_clocks BCM2835_AUX_CLOCK_SPI1>;

	#address-cells = <1>;

	#size-cells = <0>;

	cs-gpios = <&gpio 18>, <&gpio 17>, <&gpio 16>;

};

spi2@7e2150c0 {

	compatible = "brcm,bcm2835-aux-spi";

	reg = <0x7e2150c0 0x40>;

	interrupts = <1 29>;

	clocks = <&aux_clocks BCM2835_AUX_CLOCK_SPI2>;

	#address-cells = <1>;

	#size-cells = <0>;

	cs-gpios = <&gpio 43>, <&gpio 44>, <&gpio 45>;

};