armada-385-turris-omnia: enable spidev in devicetree

target/linux/mvebu/files/arch/arm/boot/dts/armada-385-turris-omnia.dts

@@ -120,6 +120,11 @@
 		};
 
 	};
+	spidev@2 {
+		spi-max-frequency = <1000000>;
+		reg = <2>;
+		compatible = "linux,spidev";
+	};
 };
 
 &i2c0 {