OpenCores tiny SPI

Required properties:
- compatible : should be "opencores,tiny-spi-rtlsvn2".
- gpios : should specify GPIOs used for chipselect.
Optional properties:
- clock-frequency : input clock frequency to the core.
- baud-width: width, in bits, of the programmable divider used to scale
	the input clock to SCLK.

The clock-frequency and baud-width properties are needed only if the divider
is programmable. They are not needed if the divider is fixed.