PM / QoS: Initial kunit test

The pm_qos family of APIs are used in relatively difficult to reproduce
scenarios such as thermal throttling so they benefit from unit testing.

Start by adding basic tests from the the freq_qos APIs. It includes
tests for issues that were brought up on mailing lists:

https://patchwork.kernel.org/patch/11252425/#23017005
https://patchwork.kernel.org/patch/11253421/

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 28b92e3..c3b3b5c 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -148,6 +148,10 @@
 	  unusable. You should say N here unless you are explicitly looking to
 	  test this functionality.
 
+config PM_QOS_KUNIT_TEST
+	bool "KUnit Test for PM QoS features"
+	depends on KUNIT
+
 config HMEM_REPORTING
 	bool
 	default n