apparmor: test: add MODULE_DESCRIPTION()

Fix the 'make W=1' warning:
WARNING: modpost: missing MODULE_DESCRIPTION() in security/apparmor/apparmor_policy_unpack_test.o
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/policy_unpack_test.c

@@ -604,4 +604,5 @@ static struct kunit_suite apparmor_policy_unpack_test_module = {
 
 kunit_test_suite(apparmor_policy_unpack_test_module);
 
+MODULE_DESCRIPTION("KUnit tests for AppArmor's policy unpack");
 MODULE_LICENSE("GPL");