TI QSPI controller.

Required properties:
- compatible : should be "ti,dra7xxx-qspi" or "ti,am4372-qspi".
- reg: Should contain QSPI registers location and length.
- #address-cells, #size-cells : Must be present if the device has sub-nodes
- ti,hwmods: Name of the hwmod associated to the QSPI

Recommended properties:
- spi-max-frequency: Definition as per
                     Documentation/devicetree/bindings/spi/spi-bus.txt

Example:

qspi: qspi@4b300000 {
	compatible = "ti,dra7xxx-qspi";
	reg = <0x4b300000 0x100>;
	#address-cells = <1>;
	#size-cells = <0>;
	spi-max-frequency = <25000000>;
	ti,hwmods = "qspi";
};