arm64: zynqmp: Wire spi-flash compatible string with flashes

Enable reading tx and rx buswidth from DT via spi-uclass.
To get these from uclass spi-flash compatible string has to be added
to flash node.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/dts/zynqmp-zcu104-revC.dts b/arch/arm/dts/zynqmp-zcu104-revC.dts
index fe742b8..becc6a0 100644
--- a/arch/arm/dts/zynqmp-zcu104-revC.dts
+++ b/arch/arm/dts/zynqmp-zcu104-revC.dts
@@ -175,7 +175,7 @@
 &qspi {
 	status = "okay";
 	flash@0 {
-		compatible = "m25p80"; /* n25q512a 128MiB */
+		compatible = "m25p80", "spi-flash"; /* n25q512a 128MiB */
 		#address-cells = <1>;
 		#size-cells = <1>;
 		reg = <0x0>;