kunit: replace KUNIT_TRIGGER_STATIC_STUB maro with KUNIT_STATIC_STUB_REDIRECT

We mix up KUNIT_TRIGGER_STATIC_STUB and KUNIT_STATIC_STUB_REDIRECT in
static_stub header. Just correct KUNIT_TRIGGER_STATIC_STUB to
KUNIT_STATIC_STUB_REDIRECT which is documented.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>