Renesas MSIOF spi controller

Required properties:
- compatible           : "renesas,msiof-r8a7743" (RZ/G1M)
			 "renesas,msiof-r8a7745" (RZ/G1E)
			 "renesas,msiof-r8a7790" (R-Car H2)
			 "renesas,msiof-r8a7791" (R-Car M2-W)
			 "renesas,msiof-r8a7792" (R-Car V2H)
			 "renesas,msiof-r8a7793" (R-Car M2-N)
			 "renesas,msiof-r8a7794" (R-Car E2)
			 "renesas,msiof-r8a7795" (R-Car H3)
			 "renesas,msiof-r8a7796" (R-Car M3-W)
			 "renesas,msiof-sh73a0" (SH-Mobile AG5)
			 "renesas,sh-mobile-msiof" (generic SH-Mobile compatibile device)
			 "renesas,rcar-gen2-msiof" (generic R-Car Gen2 and RZ/G1 compatible device)
			 "renesas,rcar-gen3-msiof" (generic R-Car Gen3 compatible device)
			 "renesas,sh-msiof"      (deprecated)

			 When compatible with the generic version, nodes
			 must list the SoC-specific version corresponding
			 to the platform first followed by the generic
			 version.

- reg                  : A list of offsets and lengths of the register sets for
			 the device.
			 If only one register set is present, it is to be used
			 by both the CPU and the DMA engine.
			 If two register sets are present, the first is to be
			 used by the CPU, and the second is to be used by the
			 DMA engine.
- interrupt-parent     : The phandle for the interrupt controller that
			 services interrupts for this device
- interrupts           : Interrupt specifier
- #address-cells       : Must be <1>
- #size-cells          : Must be <0>

Optional properties:
- clocks               : Must contain a reference to the functional clock.
- num-cs               : Total number of chip selects (default is 1).
			 Up to 3 native chip selects are supported:
			   0: MSIOF_SYNC
			   1: MSIOF_SS1
			   2: MSIOF_SS2
			 Hardware limitations related to chip selects:
			   - Native chip selects are always deasserted in
			     between transfers that are part of the same
			     message.  Use cs-gpios to work around this.
			   - All slaves using native chip selects must use the
			     same spi-cs-high configuration.  Use cs-gpios to
			     work around this.
			   - When using GPIO chip selects, at least one native
			     chip select must be left unused, as it will be
			     driven anyway.
- dmas                 : Must contain a list of two references to DMA
			 specifiers, one for transmission, and one for
			 reception.
- dma-names            : Must contain a list of two DMA names, "tx" and "rx".
- spi-slave            : Empty property indicating the SPI controller is used
			 in slave mode.
- renesas,dtdl         : delay sync signal (setup) in transmit mode.
			 Must contain one of the following values:
			 0   (no bit delay)
			 50  (0.5-clock-cycle delay)
			 100 (1-clock-cycle delay)
			 150 (1.5-clock-cycle delay)
			 200 (2-clock-cycle delay)

- renesas,syncdl       : delay sync signal (hold) in transmit mode.
			 Must contain one of the following values:
			 0   (no bit delay)
			 50  (0.5-clock-cycle delay)
			 100 (1-clock-cycle delay)
			 150 (1.5-clock-cycle delay)
			 200 (2-clock-cycle delay)
			 300 (3-clock-cycle delay)

Optional properties, deprecated for soctype-specific bindings:
- renesas,tx-fifo-size : Overrides the default tx fifo size given in words
			 (default is 64)
- renesas,rx-fifo-size : Overrides the default rx fifo size given in words
			 (default is 64)

Pinctrl properties might be needed, too.  See
Documentation/devicetree/bindings/pinctrl/renesas,*.

Example:

	msiof0: spi@e6e20000 {
		compatible = "renesas,msiof-r8a7791",
			     "renesas,rcar-gen2-msiof";
		reg = <0 0xe6e20000 0 0x0064>;
		interrupts = <0 156 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&mstp0_clks R8A7791_CLK_MSIOF0>;
		dmas = <&dmac0 0x51>, <&dmac0 0x52>;
		dma-names = "tx", "rx";
		#address-cells = <1>;
		#size-cells = <0>;
	};
