media: dev-effect.rst: remove unused Effect Interface chapter

We never had an effect interface, and if you want to do such
things you use the mem2mem interface instead.

Just drop this from the spec.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/dev-effect.rst

-.. Permission is granted to copy, distribute and/or modify this
-.. document under the terms of the GNU Free Documentation License,
-.. Version 1.1 or any later version published by the Free Software
-.. Foundation, with no Invariant Sections, no Front-Cover Texts
-.. and no Back-Cover Texts. A copy of the license is included at
-.. Documentation/media/uapi/fdl-appendix.rst.
-..
-.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
-
-.. _effect:
-
-************************
-Effect Devices Interface
-************************
-
-.. note::
-    This interface has been be suspended from the V4L2 API.
-    The implementation for such effects should be done
-    via mem2mem devices.
-
-A V4L2 video effect device can do image effects, filtering, or combine
-two or more images or image streams. For example video transitions or
-wipes. Applications send data to be processed and receive the result
-data either with :ref:`read() <func-read>` and
-:ref:`write() <func-write>` functions, or through the streaming I/O
-mechanism.
-
-[to do]

Documentation/media/uapi/v4l/devices.rst

@@ -22,7 +22,6 @@ Interfaces
     dev-output
     dev-osd
     dev-codec
-    dev-effect
     dev-raw-vbi
     dev-sliced-vbi
     dev-teletext