{cpu,soc}: Use DEVICE_NOOP macro over dummy symbol

Change-Id: Iaf2b2873bd1c52d7f936bd9b483e194a0872a626
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7285
Tested-by: build bot (Jenkins)
Reviewed-by: Bruce Griffith <Bruce.Griffith@se-eng.com>

src/soc/samsung/exynos5420/cpu.c

@@ -160,13 +160,9 @@ static void cpu_init(device_t dev)
 			cpu_id, get_arm_clk() / 1000000);
 }
 
-static void cpu_noop(device_t dev)
-{
-}
-
 static struct device_operations cpu_ops = {
-	.read_resources   = cpu_noop,
-	.set_resources    = cpu_noop,
+	.read_resources   = DEVICE_NOOP,
+	.set_resources    = DEVICE_NOOP,
 	.enable_resources = cpu_enable,
 	.init             = cpu_init,
 	.scan_bus         = 0,