ARM: dts: exynos: correct SPI nor compatible in SMDK5250

SPI NOR flash compatible should come with generic jedec,spi-nor fallback
and proper vendor prefix:

exynos5250-smdk5250.dtb: /soc/spi@12d30000/flash@0: failed to match any schema with compatible: ['w25x80']

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

arch/arm/boot/dts/exynos5250-smdk5250.dts

···
 	flash@0 {
 		#address-cells = <1>;
 		#size-cells = <1>;
-		compatible = "w25x80";
+		compatible = "winbond,w25x80", "jedec,spi-nor";
 		reg = <0>;
 		spi-max-frequency = <1000000>;