Drop an excess "`" from Documentation/driver-api/pm/devices.rst.

Fixes: 2728b2d2e5be (PM / core / docs: Convert sleep states API document to reST)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

There is a better way to represent structure references than it was
done in device.rst by commit 730c4c053012 (PM / sleep / docs: Convert
PM notifiers document to reST), which is to use "struct name" as a
link caption (e.g. :c:type:`struct device <device>`).  That will
cause sphinx to generate a proper reference to the data type in
question (struct device in the example above) and "struct name"
will work as the link in the HTML output.

Fix device.rst by using that convention where applicable.

Fixes: 730c4c053012 (PM / sleep / docs: Convert PM notifiers document to reST)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Move the document describing PM notifiers (used during system sleep
state transitions) to Documentation/driver-api/pm/, convert it to reST
and update it to use current terminology.  Also replace the remaining
references to the old version of it in .txt documents with references
to the new one.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Move the document describing the system sleep state transitions API
for devices to Documentation/driver-api/pm/, convert it to reST and
update it to use current terminology.  Also remove the remaining
reference to the old version of it from pm.h.

The new document still contains references to some documents in the
.txt format that will be converted later.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>