* Freescale Low Power SPI (LPSPI) for i.MX

Required properties:
- compatible :
  - "fsl,imx7ulp-spi" for LPSPI compatible with the one integrated on i.MX7ULP soc
  - "fsl,imx8qxp-spi" for LPSPI compatible with the one integrated on i.MX8QXP soc
- reg : address and length of the lpspi master registers
- interrupt-parent : core interrupt controller
- interrupts : lpspi interrupt
- clocks : lpspi clock specifier
- spi-slave : spi slave mode support. In slave mode, add this attribute without
	      value. In master mode, remove it.

Examples:

lpspi2: lpspi@40290000 {
	compatible = "fsl,imx7ulp-spi";
	reg = <0x40290000 0x10000>;
	interrupt-parent = <&intc>;
	interrupts = <GIC_SPI 28 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&clks IMX7ULP_CLK_LPSPI2>;
	spi-slave;
};