media: docs: Add V4L2_CAP_EDID

Add documentation for the new edid capability.

Signed-off-by: Erling Ljunggren <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Reviewed-by: Sebastian Fricke <[e-mail]>
Reviewed-by: Ricardo Ribalda <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/userspace-api/media/v4l/biblio.rst

···
 
 :author:    Video Electronics Standards Association (http://www.vesa.org)
 
+.. _vesaeddc:
+
+E-DDC
+=====
+
+
+:title:     VESA Enhanced Display Data Channel (E-DDC) Standard
+:subtitle:  Version 1.3
+
+:author:    Video Electronics Standards Association (http://www.vesa.org)
+
 .. _vesaedid:
 
 EDID

Documentation/userspace-api/media/v4l/vidioc-querycap.rst

···
       - 0x01000000
       - The device supports the :c:func:`read()` and/or
 	:c:func:`write()` I/O methods.
+    * - ``V4L2_CAP_EDID``
+      - 0x02000000
+      - The device stores the EDID for a video input, or retrieves the EDID for a video
+        output. It is a standalone EDID device, so no video streaming etc. will take place.
+
+        For a video input this is typically an eeprom that supports the
+        :ref:`VESA Enhanced Display Data Channel Standard <vesaeddc>`. It can be something
+        else as well, for example a micro controller.
+
+        For a video output this is typically read from an external device such as an
+        HDMI splitter accessed by a serial port.
     * - ``V4L2_CAP_STREAMING``
       - 0x04000000
       - The device supports the :ref:`streaming <mmap>` I/O method.

Documentation/userspace-api/media/videodev2.h.rst.exceptions

···
 replace define V4L2_CAP_DEVICE_CAPS device-capabilities
 replace define V4L2_CAP_TOUCH device-capabilities
 replace define V4L2_CAP_IO_MC device-capabilities
+replace define V4L2_CAP_EDID device-capabilities
 
 # V4L2 pix flags
 replace define V4L2_PIX_FMT_PRIV_MAGIC :c:type:`v4l2_pix_format`