Documentation: gpu: Use internal link to kunit

Use internal linking to kunit documentation.

Signed-off-by: Bagas Sanjaya <[email protected]>
Acked-by: Thomas Zimmermann <[email protected]>

Author: bagasme

Documentation/gpu/todo.rst

@@ -655,9 +655,9 @@ Better Testing
 Add unit tests using the Kernel Unit Testing (KUnit) framework
 --------------------------------------------------------------
 
-The `KUnit <https://www.kernel.org/doc/html/latest/dev-tools/kunit/index.html>`_
-provides a common framework for unit tests within the Linux kernel. Having a
-test suite would allow to identify regressions earlier.
+The :doc:`KUnit </dev-tools/kunit/index>` provides a common framework for unit
+tests within the Linux kernel. Having a test suite would allow to identify
+regressions earlier.
 
 A good candidate for the first unit tests are the format-conversion helpers in
 ``drm_format_helper.c``.