spi: dw: Add SoC-specific compatible strings

This adds SoC-specific compatible strings to all users of the designware
spi device. This will allow for the correct driver to be selected for each
device. Where it is publicly documented, a compatible string for the
specific device version has also been added. Devices without
publicly-documented device versions include MSCC SoCs, and Arc Socs. All
compatible strings except those for SoCFPGAs and some of the versioned
strings have been taken from Linux.

Since SSI_MAX_XFER_SIZE is determined at runtime, this is not strictly
necessary. However, it is a good cleanup and brings things closer to Linux.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Tested-by Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/arch/mips/dts/mscc,ocelot.dtsi b/arch/mips/dts/mscc,ocelot.dtsi
index 9a187b6..aeb4bf8 100644
--- a/arch/mips/dts/mscc,ocelot.dtsi
+++ b/arch/mips/dts/mscc,ocelot.dtsi
@@ -100,7 +100,7 @@
 		spi0: spi-master@101000 {
 			#address-cells = <1>;
 			#size-cells = <0>;
-			compatible = "snps,dw-apb-ssi";
+			compatible = "mscc,ocelot-spi", "snps,dw-apb-ssi";
 			reg = <0x101000 0x40>;
 			num-chipselect = <4>;
 			bus-num = <0>;