[media] media: DocBook: Fix trivial typo in Sub-device Interface

When satisfied with the try results, applications can set the active formats
by setting the which argument to V4L2_SUBDEV_FORMAT_ACTIVE
not V4L2_SUBDEV_FORMAT_TRY.
Signed-off-by: Jonghun Han <jonghun.han@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/v4l/dev-subdev.xml

@@ -266,7 +266,7 @@
 
       <para>When satisfied with the try results, applications can set the active
       formats by setting the <structfield>which</structfield> argument to
-      <constant>V4L2_SUBDEV_FORMAT_TRY</constant>. Active formats are changed
+      <constant>V4L2_SUBDEV_FORMAT_ACTIVE</constant>. Active formats are changed
       exactly as try formats by drivers. To avoid modifying the hardware state
       during format negotiation, applications should negotiate try formats first
       and then modify the active settings using the try formats returned during