Renesas MSIOF spi controller

Required properties:
- compatible : 	"renesas,sh-msiof" for SuperH or
		"renesas,sh-mobile-msiof" for SH Mobile series
- reg : Offset and length of the register set for the device
- interrupts : interrupt line used by MSIOF

Optional properties:
- num-cs		: total number of chip-selects
- renesas,tx-fifo-size	: Overrides the default tx fifo size given in words
- renesas,rx-fifo-size	: Overrides the default rx fifo size given in words