fortify: test: Use kunit_device

Using struct root_device to create fake devices for tests is something
of a hack. The new struct kunit_device is meant for this purpose, so use
it instead.
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/fortify_kunit.c

@@ -15,6 +15,7 @@
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <kunit/device.h>
 #include <kunit/test.h>
 #include <linux/device.h>
 #include <linux/slab.h>
@@ -269,7 +270,7 @@ DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
 	size_t len;							\
 									\
 	/* Create dummy device for devm_kmalloc()-family tests. */	\
-	dev = root_device_register(dev_name);				\
+	dev = kunit_device_register(test, dev_name);			\
 	KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev),			\
 			       "Cannot register test device\n");	\
 									\
@@ -303,7 +304,7 @@ DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
 	checker(len, devm_kmemdup(dev, "Ohai", len, gfp),		\
 		devm_kfree(dev, p));					\
 									\
-	device_unregister(dev);						\
+	kunit_device_unregister(test, dev);				\
 } while (0)
 DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)