arm64: dts: cix: add a compatible string for the cix sky1 SoC

The SPI IP design for the cix sky1 SoC uses a FIFO with a data width
of 32 bits, instead of the default 8 bits. Therefore, a compatible
string is added to specify the FIFO data width configuration for the
cix sky1 SoC.

Signed-off-by: Jun Guo <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Peter Chen <[e-mail]>

arch/arm64/boot/dts/cix/sky1.dtsi

···
 		};
 
 		spi0: spi@4090000 {
-			compatible = "cdns,spi-r1p6";
+			compatible = "cix,sky1-spi-r1p6", "cdns,spi-r1p6";
 			reg = <0x0 0x04090000 0x0 0x10000>;
 			clocks = <&scmi_clk CLK_TREE_FCH_SPI0_APB>,
 				 <&scmi_clk CLK_TREE_FCH_SPI0_APB>;
···
 		};
 
 		spi1: spi@40a0000 {
-			compatible = "cdns,spi-r1p6";
+			compatible = "cix,sky1-spi-r1p6", "cdns,spi-r1p6";
 			reg = <0x0 0x040a0000 0x0 0x10000>;
 			clocks = <&scmi_clk CLK_TREE_FCH_SPI1_APB>,
 				 <&scmi_clk CLK_TREE_FCH_SPI1_APB>;