media: staging: media: Revert "media: zoran: remove deprecated driver"

This reverts commit 8dce4b26.
The revert is slighly modified:
- Documentation/media/v4l-drivers/index.rst is ,ot restored since removed from tree
- drivers/staging/media/Makefile is not restored since the zoran driver
  is not compilable yet.

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>