Microchip PIC32 Quad SPI controller
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Required properties:
- compatible: Should be "microchip,pic32mzda-sqi".
- reg: Address and length of SQI controller register space.
- interrupts: Should contain SQI interrupt.
- clocks: Should contain phandle of two clocks in sequence, one that drives
          clock on SPI bus and other that drives SQI controller.
- clock-names: Should be "spi_ck" and "reg_ck" in order.

Example:
	sqi1: spi@1f8e2000 {
		compatible = "microchip,pic32mzda-sqi";
		reg = <0x1f8e2000 0x200>;
		clocks = <&rootclk REF2CLK>, <&rootclk PB5CLK>;
		clock-names = "spi_ck", "reg_ck";
		interrupts = <169 IRQ_TYPE_LEVEL_HIGH>;
	};
