[media] V4L: Add V4L2_ASYNC_MATCH_OF subdev matching type

Add support for matching by device_node pointer. This allows
the notifier user to simply pass a list of device_node pointers
corresponding to sub-devices.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
index 33e3b2a..82b2981 100644
--- a/include/media/v4l2-async.h
+++ b/include/media/v4l2-async.h
@@ -15,6 +15,7 @@
 #include <linux/mutex.h>
 
 struct device;
+struct device_node;
 struct v4l2_device;
 struct v4l2_subdev;
 struct v4l2_async_notifier;
@@ -26,6 +27,7 @@
 	V4L2_ASYNC_MATCH_CUSTOM,
 	V4L2_ASYNC_MATCH_DEVNAME,
 	V4L2_ASYNC_MATCH_I2C,
+	V4L2_ASYNC_MATCH_OF,
 };
 
 /**
@@ -39,6 +41,9 @@
 	enum v4l2_async_match_type match_type;
 	union {
 		struct {
+			const struct device_node *node;
+		} of;
+		struct {
 			const char *name;
 		} device_name;
 		struct {