docs: devices.rst: better reference documentation docs

There's no need to use either :file: or :doc: tags for documentation,
as automarkup.py automatically converts Documentation/*.rst into
a cross-reference.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/5d9c9949a104d10b537a2d780bccad69a2dc58f9.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/driver-api/pm/devices.rst

@@ -217,7 +217,7 @@ system-wide transition to a sleep state even though its :c:member:`runtime_auto`
 flag is clear.
 
 For more information about the runtime power management framework, refer to
-:file:`Documentation/power/runtime_pm.rst`.
+Documentation/power/runtime_pm.rst.
 
 
 Calling Drivers to Enter and Leave System Sleep States
@@ -655,7 +655,7 @@ been thawed.  Generally speaking, the PM notifiers are suitable for performing
 actions that either require user space to be available, or at least won't
 interfere with user space.
 
-For details refer to :doc:`notifiers`.
+For details refer to Documentation/driver-api/pm/notifiers.rst.
 
 
 Device Low-Power (suspend) States
@@ -726,7 +726,7 @@ it into account in any way.
 
 Devices may be defined as IRQ-safe which indicates to the PM core that their
 runtime PM callbacks may be invoked with disabled interrupts (see
-:file:`Documentation/power/runtime_pm.rst` for more information).  If an
+Documentation/power/runtime_pm.rst for more information).  If an
 IRQ-safe device belongs to a PM domain, the runtime PM of the domain will be
 disallowed, unless the domain itself is defined as IRQ-safe. However, it
 makes sense to define a PM domain as IRQ-safe only if all the devices in it
@@ -805,7 +805,7 @@ The ``DPM_FLAG_MAY_SKIP_RESUME`` Driver Flag
 --------------------------------------------
 
 During system-wide resume from a sleep state it's easiest to put devices into
-the full-power state, as explained in :file:`Documentation/power/runtime_pm.rst`.
+the full-power state, as explained in Documentation/power/runtime_pm.rst.
 [Refer to that document for more information regarding this particular issue as
 well as for information on the device runtime power management framework in
 general.]  However, it often is desirable to leave devices in suspend after