m68k: dts: stmark2: set correct compatible field for spi nor

Fix error:

Invalid chip select 0:1 (err=-19)

update spi nor "compatible" property with "jedec,spi-nor"
to have spi nor properly bound as a child device.

Signed-off-by: Angelo Durgehello <angelo@kernel-space.org>

arch/m68k/dts/stmark2.dts

@@ -27,7 +27,7 @@
 	flash: is25lp128@1 {
 		#address-cells = <1>;
 		#size-cells = <1>;
-		compatible = "spi-flash";
+		compatible = "jedec,spi-nor";
 		spi-max-frequency = <60000000>;
 		reg = <1>;
 	};