kcsan: Add missing MODULE_DESCRIPTION() macro

Fix the warning reported by 'make C=1 W=1':
WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/kcsan/kcsan_test.o
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/kcsan/kcsan_test.c

@@ -1620,5 +1620,6 @@ static struct kunit_suite kcsan_test_suite = {
 
 kunit_test_suites(&kcsan_test_suite);
 
+MODULE_DESCRIPTION("KCSAN test suite");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Marco Elver <elver@google.com>");