selftests/futex: futex_waitv wouldblock test should fail

Testcase should fail if -EWOULDBLOCK is not returned when expected value
differs from actual value from the waiter.

Link: https://lore.kernel.org/r/20250404221225.1596324-1-edliaw@google.com


Fixes: 9d57f7c7 ("selftests: futex: Test sys_futex_waitv() wouldblock")
Signed-off-by: Edward Liaw <edliaw@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>