riscv: dts: sophgo: Add spi nor flash controller node

Add spi nor flash controller node for cv18xx SoCs

Signed-off-by: Kongyang Liu <seashell11234455@gmail.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/dts/cv1800b-milkv-duo.dts b/arch/riscv/dts/cv1800b-milkv-duo.dts
index f6ae882..e7cc0e8 100644
--- a/arch/riscv/dts/cv1800b-milkv-duo.dts
+++ b/arch/riscv/dts/cv1800b-milkv-duo.dts
@@ -46,6 +46,19 @@
 	no-sdio;
 };
 
+&spif {
+	status = "okay";
+
+	spiflash@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+		spi-max-frequency = <75000000>;
+		spi-tx-bus-width = <4>;
+		spi-rx-bus-width = <4>;
+		m25p,fast-read;
+	};
+};
+
 &uart0 {
 	status = "okay";
 };