iot_dk/hsdk: Implement its own print_cpuinfo()

ARC IDENTITY register only encodes major architecture
type and version while for a particular board/silicon we
may know better which template was used and so we may identify
CPU more precise, which exactly we do here.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

board/synopsys/iot_devkit/iot_devkit.c

@@ -166,3 +166,11 @@ int checkboard(void)
 	puts("Board: Synopsys IoT Development Kit\n");
 	return 0;
 };
+
+#ifdef CONFIG_DISPLAY_CPUINFO
+int print_cpuinfo(void)
+{
+	printf("CPU:   ARC EM9D\n");
+	return 0;
+}
+#endif /* CONFIG_DISPLAY_CPUINFO */