OMAP2+ McSPI device

Required properties:
- compatible :
  - "ti,omap2-spi" for OMAP2 & OMAP3.
  - "ti,omap4-spi" for OMAP4+.
- ti,spi-num-cs : Number of chipselect supported  by the instance.
- ti,hwmods: Name of the hwmod associated to the McSPI


Example:

mcspi1: mcspi@1 {
    #address-cells = <1>;
    #size-cells = <0>;
    compatible = "ti,omap4-mcspi";
    ti,hwmods = "mcspi1";
    ti,spi-num-cs = <4>;
};