arm64: xilinx: Remove mt25qu512a compatible string from SOM

mt25qu512a is not documented in DT binding that's why remove it.
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/a1e975f5785dfb6eb04e8d5905dcaa7467ccd585.1695040866.git.michal.simek@amd.com

arch/arm64/boot/dts/xilinx/zynqmp-sm-k26-revA.dts

@@ -131,7 +131,7 @@ mux {
 &qspi { /* MIO 0-5 - U143 */
 	status = "okay";
 	spi_flash: flash@0 { /* MT25QU512A */
-		compatible = "mt25qu512a", "jedec,spi-nor"; /* 64MB */
+		compatible = "jedec,spi-nor"; /* 64MB */
 		#address-cells = <1>;
 		#size-cells = <1>;
 		reg = <0>;