kunit: add missing MODULE_DESCRIPTION() macros to core modules

make allmodconfig && make W=1 C=1 reports in lib/kunit:
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/kunit/kunit.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/kunit/kunit-test.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/kunit/kunit-example-test.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson <[e-mail]>
Reviewed-by: Rae Moar <[e-mail]>
Reviewed-by: David Gow <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

lib/kunit/kunit-example-test.c

···
  */
 kunit_test_init_section_suites(&example_init_test_suite);
 
+MODULE_DESCRIPTION("Example KUnit test suite");
 MODULE_LICENSE("GPL v2");

lib/kunit/kunit-test.c

···
 		  &kunit_current_test_suite, &kunit_device_test_suite,
 		  &kunit_fault_test_suite);
 
+MODULE_DESCRIPTION("KUnit test for core test infrastructure");
 MODULE_LICENSE("GPL v2");

lib/kunit/test.c

···
 }
 module_exit(kunit_exit);
 
+MODULE_DESCRIPTION("Base unit test (KUnit) API");
 MODULE_LICENSE("GPL v2");