docs: i2c: 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: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/569722e3f7d73d746c145ea78d2b4fbe5defee90.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/i2c/old-module-parameters.rst b/Documentation/i2c/old-module-parameters.rst
index 38e5582..b08b6da 100644
--- a/Documentation/i2c/old-module-parameters.rst
+++ b/Documentation/i2c/old-module-parameters.rst
@@ -17,7 +17,8 @@
 With the conversion of the I2C subsystem to the standard device driver
 binding model, it became clear that these per-module parameters were no
 longer needed, and that a centralized implementation was possible. The new,
-sysfs-based interface is described in :doc:`instantiating-devices`, section
+sysfs-based interface is described in
+Documentation/i2c/instantiating-devices.rst, section
 "Method 4: Instantiate from user-space".
 
 Below is a mapping from the old module parameters to the new interface.