arm64: dts: rockchip: enable onboard spi flash for rock-3a

There is a mx25u12835f spi flash on this board, enable it.

[    2.525805] spi-nor spi4.0: mx25u12835f (16384 Kbytes)
Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Link: https://lore.kernel.org/r/20240409120003.309358-2-amadeus@jmu.edu.cnSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts

@@ -757,6 +757,20 @@ &sdmmc2 {
 	status = "okay";
 };
 
+&sfc {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	status = "okay";
+
+	flash@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0x0>;
+		spi-max-frequency = <104000000>;
+		spi-rx-bus-width = <4>;
+		spi-tx-bus-width = <1>;
+	};
+};
+
 &tsadc {
 	rockchip,hw-tshut-mode = <1>;
 	rockchip,hw-tshut-polarity = <0>;