docs: driver-api: surface_aggregator: avoid using ReST :doc:`foo` markup

The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.

Acked-by: Maximilian Luz <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>
Link: https://lore.kernel.org/r/609702[e-mail]
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/driver-api/surface_aggregator/clients/index.rst

···
 ===========================
 
 This is the documentation for client drivers themselves. Refer to
-:doc:`../client` for documentation on how to write client drivers.
+Documentation/driver-api/surface_aggregator/client.rst for documentation
+on how to write client drivers.
 
 .. toctree::
    :maxdepth: 1

Documentation/driver-api/surface_aggregator/internal.rst

···
 implemented as platform devices, via |ssam_device| and |ssam_device_driver|
 simplify management of client devices and client drivers.
 
-Refer to :doc:`client` for documentation regarding the client device/driver
-API and interface options for other kernel drivers. It is recommended to
-familiarize oneself with that chapter and the :doc:`ssh` before continuing
-with the architectural overview below.
+Refer to Documentation/driver-api/surface_aggregator/client.rst for
+documentation regarding the client device/driver API and interface options
+for other kernel drivers. It is recommended to familiarize oneself with
+that chapter and the Documentation/driver-api/surface_aggregator/ssh.rst
+before continuing with the architectural overview below.
 
 
 Packet Transport Layer
···
 
 Transmission of sequenced packets is limited by the number of concurrently
 pending packets, i.e. a limit on how many packets may be waiting for an ACK
-from the EC in parallel. This limit is currently set to one (see :doc:`ssh`
-for the reasoning behind this). Control packets (i.e. ACK and NAK) can
-always be transmitted.
+from the EC in parallel. This limit is currently set to one (see
+Documentation/driver-api/surface_aggregator/ssh.rst for the reasoning behind
+this). Control packets (i.e. ACK and NAK) can always be transmitted.
 
 Receiver Thread
 ---------------

Documentation/driver-api/surface_aggregator/overview.rst

···
 without response as commands. In general, events need to be enabled via one
 of multiple dedicated requests before they are sent by the EC.
 
-See :doc:`ssh` for a more technical protocol documentation and
-:doc:`internal` for an overview of the internal driver architecture.
+See Documentation/driver-api/surface_aggregator/ssh.rst for a
+more technical protocol documentation and
+Documentation/driver-api/surface_aggregator/internal.rst for an
+overview of the internal driver architecture.