Convert all text files with s390 documentation to ReST format.

Tried to preserve as much as possible the original document
format. Still, some of the files required some work in order
for it to be visible on both plain text and after converted
to html.

The conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Also mention the iv helpers as well.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Since the original inception of the s390-drivers document, the
common I/O layer has grown support for more types of subchannels.
Give at least a pointer for the various types.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Back in 2012, commit 9807f75955ea (UAPI: (Scripted) Disintegrate
arch/s390/include/asm) moved struct cmbdata (and its kerneldoc comments) to
another file, but did not update the docs to match.  The result is this
warning:

    ./arch/s390/include/asm/cmb.h:1: warning: no structured comments found

...and no documentation for that structure.  Update the docs to get the
information from the right place.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Use pandoc to convert documentation to ReST by calling
Documentation/sphinx/tmplcvt script.

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>