Exynos ISP SPI Subsystem

The device node for ISP SPI subsytem.
Since Peripheral id in EXYNOS is decoded based on Interrupts, currently
ISP SPI have no individual interrupts hence we add ad dummy interrupt node
which will have a value beyond the maximum number of interrupts exynos5 can
support.

Required properties :
 - compatible : Should be "samsung,exynos-spi" for spi.
 - reg : Base adrress of the the subsystem.
 - interrupts : A value which is beyond the maximum number of interrupts
exynos5 can support.

Example:
spi@131a0000 {
	#address-cells = <1>;
	#size-cells = <0>;
	compatible = "samsung,exynos-spi";
	reg = <0x131a0000 0x30>;
	interrupts = <0 129 0>;
};