dt: bcm963158: add a spi-nor device

This change adds a spi nor flash device to the bcm963158 board.

Signed-off-by: Kursad Oney <kursad.oney@broadcom.com>
Reviewed-by: Philippe Reynes <philippe.reynes@softathome.com>

arch/arm/dts/bcm963158.dts

@@ -125,3 +125,15 @@
 		label = "green:aggregate_link";
 	};
 };
+
+&hsspi {
+	status = "okay";
+
+	flash: mt25@0 {
+		compatible = "jedec,spi-nor";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		reg = <0>;
+		spi-max-frequency = <25000000>;
+	};
+};