* Atmel Quad Serial Peripheral Interface (QSPI)

Required properties:
- compatible:     Should be "atmel,sama5d2-qspi".
- reg:            Should contain the locations and lengths of the base registers
                  and the mapped memory.
- reg-names:      Should contain the resource reg names:
                  - qspi_base: configuration register address space
                  - qspi_mmap: memory mapped address space
- interrupts:     Should contain the interrupt for the device.
- clocks:         The phandle of the clock needed by the QSPI controller.
- #address-cells: Should be <1>.
- #size-cells:    Should be <0>.

Example:

spi@f0020000 {
	compatible = "atmel,sama5d2-qspi";
	reg = <0xf0020000 0x100>, <0xd0000000 0x8000000>;
	reg-names = "qspi_base", "qspi_mmap";
	interrupts = <52 IRQ_TYPE_LEVEL_HIGH 7>;
	clocks = <&spi0_clk>;
	#address-cells = <1>;
	#size-cells = <0>;
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_spi0_default>;
	status = "okay";

	m25p80@0 {
		...
	};
};