pm: device_runtime: Fix tracing in runtime_enable

Move around SYS_PORT_FUNC_ENTER and change a early return
in a way that when this function is called it will generate
tracing for entering / leaving this function.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

subsys/pm/device_runtime.c

@@ -416,12 +416,13 @@ int pm_device_runtime_enable(const struct device *dev)
 	int ret = 0;
 	struct pm_device *pm = dev->pm;
 
+	SYS_PORT_TRACING_FUNC_ENTER(pm, device_runtime_enable, dev);
+
 	if (pm == NULL) {
-		return -ENOTSUP;
+		ret = -ENOTSUP;
+		goto end;
 	}
 
-	SYS_PORT_TRACING_FUNC_ENTER(pm, device_runtime_enable, dev);
-
 	if (pm_device_state_is_locked(dev)) {
 		ret = -EPERM;
 		goto end;