clk: Add test managed clk provider/consumer APIs

Unit tests are more ergonomic and simpler to understand if they don't
have to hoist a bunch of code into the test harness init and exit
functions. Add some test managed wrappers for the clk APIs so that clk
unit tests can write more code in the actual test and less code in the
harness.

Only add APIs that are used for now. More wrappers can be added in the
future as necessary.

Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20240718210513.3801024-7-sboyd@kernel.org

Documentation/dev-tools/kunit/api/clk.rst

@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========
+Clk API
+========
+
+The KUnit clk API is used to test clk providers and clk consumers.
+
+.. kernel-doc:: drivers/clk/clk_kunit_helpers.c
+   :export:

Documentation/dev-tools/kunit/api/index.rst

@@ -9,6 +9,7 @@ API Reference
 	test
 	resource
 	functionredirection
+	clk
 	of
 	platformdevice
 
@@ -34,6 +35,10 @@ Documentation/dev-tools/kunit/api/functionredirection.rst
 Driver KUnit API
 ================
 
+Documentation/dev-tools/kunit/api/clk.rst
+
+ - Documents the KUnit clk API
+
 Documentation/dev-tools/kunit/api/of.rst
 
  - Documents the KUnit device tree (OF) API