device property: check fwnode type in to_of_node()

Potentially one of platform can support both ACPI and OF. In that case when we
call to_of_node() for non-OF fwnode types we will get non-NULL result, which is
wrong. Check for the type and return a correspondent result.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/of.h

@@ -136,7 +136,8 @@ static inline bool is_of_node(struct fwnode_handle *fwnode)
 
 static inline struct device_node *to_of_node(struct fwnode_handle *fwnode)
 {
-	return fwnode ? container_of(fwnode, struct device_node, fwnode) : NULL;
+	return is_of_node(fwnode) ?
+		container_of(fwnode, struct device_node, fwnode) : NULL;
 }
 
 static inline bool of_have_populated_dt(void)