default to 0

target/linux/config/Config.in.flash

@@ -138,4 +138,4 @@ config ADK_TARGET_MTD_SIZE
 	int
 	default "33554432" if ADK_TARGET_SYSTEM_QEMU_MICROBLAZE	
 	default "33554432" if ADK_TARGET_SYSTEM_QEMU_MICROBLAZEEL
-	default ""
+	default "0"