arm64: dts: ls1028a: fix FlexSPI clock

Now that we have a proper driver for the FlexSPI interface use it. This
will fix SCK frequency switching on Layerscape SoCs.

This was tested on the Kontron sl28 board.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/fsl-ls1028a.dtsi

@@ -206,9 +206,20 @@ ddr: memory-controller@1080000 {
 		};
 
 		dcfg: syscon@1e00000 {
-			compatible = "fsl,ls1028a-dcfg", "syscon";
+			#address-cells = <1>;
+			#size-cells = <1>;
+			compatible = "fsl,ls1028a-dcfg", "syscon", "simple-mfd";
 			reg = <0x0 0x1e00000 0x0 0x10000>;
+			ranges = <0x0 0x0 0x1e00000 0x10000>;
 			little-endian;
+
+			fspi_clk: clock-controller@900 {
+				compatible = "fsl,ls1028a-flexspi-clk";
+				reg = <0x900 0x4>;
+				#clock-cells = <0>;
+				clocks = <&clockgen QORIQ_CLK_HWACCEL 0>;
+				clock-output-names = "fspi_clk";
+			};
 		};
 
 		rst: syscon@1e60000 {
@@ -326,8 +337,7 @@ fspi: spi@20c0000 {
 			      <0x0 0x20000000 0x0 0x10000000>;
 			reg-names = "fspi_base", "fspi_mmap";
 			interrupts = <GIC_SPI 25 IRQ_TYPE_LEVEL_HIGH>;
-			clocks = <&clockgen QORIQ_CLK_HWACCEL 0>,
-				 <&clockgen QORIQ_CLK_HWACCEL 0>;
+			clocks = <&fspi_clk>, <&fspi_clk>;
 			clock-names = "fspi_en", "fspi";
 			status = "disabled";
 		};