xilinx: Add jedec compatible string for QSPI (Zynq/ZynqMP)

Add missing "jedec, spi-nor" compatible string for QSPI flash node.
Spi-nor framework uses this compatibility string to probe &
initialize flash. With missing compatibility string we are observing
below error:

Zynq> sf probe 0 0 0
 jedec_spi_nor spi_flash@0:0: unrecognized JEDEC id bytes:
00, 00, 00  Failed to initialize SPI flash at 0:0 (error -2)

Signed-off-by: Raju Kumar Pothuraju <raju.kumar-pothuraju@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/dts/zynq-cse-qspi.dtsi b/arch/arm/dts/zynq-cse-qspi.dtsi
index eb0e29e..38410ee 100644
--- a/arch/arm/dts/zynq-cse-qspi.dtsi
+++ b/arch/arm/dts/zynq-cse-qspi.dtsi
@@ -60,7 +60,7 @@
 			#size-cells = <0>;
 			num-cs = <1>;
 			flash0: flash@0 {
-				compatible = "n25q128a11";
+				compatible = "n25q128a11", "jedec,spi-nor";
 				reg = <0x0>;
 				spi-tx-bus-width = <1>;
 				spi-rx-bus-width = <4>;