Convert this small file to ReST in preparation for adding it to
the driver-api book.

While this is not part of the driver-api book, mark it as
:orphan:, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>