media: v4l2-subdev.rst: correct information about v4l2 events

Remove description of non-existing v4l2_subdev.nevents and replace the
undefined flag V4L2_SUBDEV_USES_EVENTS by the correct flag
V4L2_SUBDEV_FL_HAS_EVENTS, which is already documented in v4l2_subdev.flags

Fixes: commit 02adb1c ("[media] v4l: subdev: Events support")
Signed-off-by: Michael Rodin <mrodin@de.adit-jv.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Author: Michael Rodin

Documentation/driver-api/media/v4l2-subdev.rst

@@ -319,8 +319,7 @@ The device node handles a subset of the V4L2 API.
 	events can also be reported by one (or several) V4L2 device nodes.
 
 	Sub-device drivers that want to use events need to set the
-	``V4L2_SUBDEV_USES_EVENTS`` :c:type:`v4l2_subdev`.flags and initialize
-	:c:type:`v4l2_subdev`.nevents to events queue depth before registering
+	``V4L2_SUBDEV_FL_HAS_EVENTS`` :c:type:`v4l2_subdev`.flags before registering
 	the sub-device. After registration events can be queued as usual on the
 	:c:type:`v4l2_subdev`.devnode device node.