ARM: dts: ast2500-evb: fix board compatible

The AST2500 EVB board should have dedicated compatible.

Fixes: 02440622 ("arm/dst: Add Aspeed ast2500 device tree")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220529104928.79636-4-krzysztof.kozlowski@linaro.org

arch/arm/boot/dts/aspeed-ast2500-evb.dts

@@ -5,7 +5,7 @@
 
 / {
 	model = "AST2500 EVB";
-	compatible = "aspeed,ast2500";
+	compatible = "aspeed,ast2500-evb", "aspeed,ast2500";
 
 	aliases {
 		serial4 = &uart5;