GENI based Qualcomm Universal Peripheral (QUP) Serial Peripheral Interface (SPI)

The QUP v3 core is a GENI based AHB slave that provides a common data path
(an output FIFO and an input FIFO) for serial peripheral interface (SPI)
mini-core.

SPI in master mode supports up to 50MHz, up to four chip selects, programmable
data path from 4 bits to 32 bits and numerous protocol variants.

Required properties:
- compatible:		Must contain "qcom,geni-spi".
- reg:			Must contain SPI register location and length.
- interrupts:		Must contain SPI controller interrupts.
- clock-names:		Must contain "se".
- clocks:		Serial engine core clock needed by the device.
- #address-cells:	Must be <1> to define a chip select address on
			the SPI bus.
- #size-cells:		Must be <0>.

SPI Controller nodes must be child of GENI based Qualcomm Universal
Peripharal. Please refer GENI based QUP wrapper controller node bindings
described in Documentation/devicetree/bindings/soc/qcom/qcom,geni-se.txt.

SPI slave nodes must be children of the SPI master node and conform to SPI bus
binding as described in Documentation/devicetree/bindings/spi/spi-bus.txt.

Example:
	spi0: spi@a84000 {
		compatible = "qcom,geni-spi";
		reg = <0xa84000 0x4000>;
		interrupts = <GIC_SPI 354 IRQ_TYPE_LEVEL_HIGH>;
		clock-names = "se";
		clocks = <&clock_gcc GCC_QUPV3_WRAP0_S0_CLK>;
		pinctrl-names = "default", "sleep";
		pinctrl-0 = <&qup_1_spi_2_active>;
		pinctrl-1 = <&qup_1_spi_2_sleep>;
		#address-cells = <1>;
		#size-cells = <0>;
	};